I also read somewhere that they were testing whether they could replace or have less of Gillian and put in that British actress. But DD did not get along well with her. Maybe because he had an inkling they were "auditioning" her for a bigger role in the X-Files. They were constantly trying to replace Gillian in that first season lol.
Did CC Intend to Replace Gillian?
Here's the thing: I've recently come to doubt that claim's authenticity.
(tl;dr at the end.)
SHORT BACKSTORY
Per Chris Carter, he knew Gillian was Scully immediately; and fought for her before the pilot and during her pregnancy. If one doesn't fully trust his word (understandable), then refer to Gillian herself, who confirmed-- along with multiple writers, directors, and other actors-- this version of events independently and repeatedly (some quotes here.)
We can prove Gillian isn't sparing anyone's reputation because she often talks about other (my words) cruel producers who had no bones about keeping her in line or threatening her job security. She has never, to my knowledge, lumped Chris Carter in with the replacement crowd-- and she's also never been shy discussing her hardships professionally or her frustrations with CC personally, on or off contract.
Now, CC did intend to turn Phoebe into a recurring character, but not as a serious love interest.
Per The Official Guide to The X-Files, Vol. 1--
The character of Phoebe Green--played by Amanda Pays [...]--was considered as a possible recurring role, owing to Carter's admiration for the actress and his love of Sherlock Holmes. Carter was intrigued by the idea of incorporating a Scotland Yard detective into the show. The chemistry "didn't work as it might," he says, though Phoebe did achieve the desired effect by becoming a character, as Carter puts it, "who fans on the Internet loved to hate."
The original script included a closing exchange where Scully observes, "Well, never let it be said that you wouldn't walk through fire for a woman, Mulder," to which he replies, "And never let it be said that I wouldn't do it for you again, Scully."
In short, she was an early draft of Diana Fowley.
As for replacing Gillian, the one authenticated quote discussing this theory comes from none other than Glen Morgan--
May 2002:
MORGAN People will deny it, but [during the first season] they thought Gillian was not up to David's snuff. There was "Fire" [episode 11, about a pyromaniac], with Amanda Pays, and Chris was taking a look to see if maybe [Pays] should replace her. [But] James and I thought Gillian was terrific. She just didn't have anything to do. So we wrote "Beyond the Sea" to show what she was capable of.
MY DOUBTS
There are a few problems with Glen's assertion.
It's tempting to trust Glen Morgan's report over Chris Carter's-- he's a generally forthright guy.
But if true, you'd have to believe that CC told the same lie, word for word, for over thirty years (when he's spinning falsehoods, the story changes.) A lie which, most importantly, was corroborated by everyone else but Morgan. When he cast Gillian as Scully, he wanted her and her alone for the role: why would CC suddenly pivot if his original design for the series-- alien stories-- suited Duchovny's and Anderson's abilities just fine? Why would he effusively praise both actors (despite how "green," etc.) if seeking a replacement?
Another issue I have with GM's account. Although present for Season 1, Morgan was not generally aligned with CC's vision... nor, perhaps, even aware of it (post here, here, and here)?
Case in point: when he and James Wong briefly returned for Season 4, Morgan was surprised that the writers were highlighting MSR's romantic undertones. To him, the relationship had always been strictly platonic, one which might turn (my words) toxic if it ever came to pass. This, I believe, led to the creation of Melissa Scully as a romantic option (nixed by Carter) and Melissa Riedel-Ephesian as an endless soulmate (with greater romantic dominance than Scully in the soulmate triangle.) Not to mention Morgan's Never Again retrospective: "My gut feeling is that Scully does see Mulder as a father figure,” Morgan said. “Sometimes he treats her like a younger sister, and an older sibling can teach you about the specifics; how to dress, who to talk to, what to say. But fathers and parents can teach you about the greater things of life. I think, when you get right down to it, that’s what Mulder has opened up in her. In ‘Never Again, ” I don’t know if she’s rejecting the message, but she’s rejecting the father.")
But we know CC always planned to have that sexual, kiss-when-the-series-ends tension simmering under The X-Files's surface: it was written into the very fiber of Mulder and Scully's dynamic (which I've discussed ad nauseam, posts here, here, here, and here.)
Furthermore, everyone else got the memo. DD and GA (but especially Gillian) talked about the sexual tension between the characters as early as Season 1, with the strong caveat that more couldn't be done for the show's sake... with an underlined, asterisk-ed yet. (I've also written many posts from their perspectives: here, here, and here.) The writers knew. The directors knew. The set designers probably knew. The public and the reviewers sensed it. M/S was all-but-confirmation for years.
Yet Glen Morgan was surprised by it (and still reluctantly on board as late as 2024, per this podcast.) Which means he was, somehow, out of the loop. And if he was out of the loop on the key part of the show-- i.e. intended sexual tension, not just platonic chemistry-- then, well....
Even more astonishing: when Glen Morgan and James Wong were brought back under contract for Season 4, they took the rough draft-- i.e. something comes between Mulder and Scully-- in a completely different direction than the other writers. Morgan's plan was for Mulder and Scully to stop communicating, drift apart, and crack their partnership to the point of near irreconcilability; Spotnitz and the other writers (with CC's approval) thought up the cancer arc instead. To Morgan, Never Again was Mulder and Scully's jumping-off point (one buoyed by Home, i.e. how little they knew each other, and The Field Where I Died-Never Again, i.e. a third party coming between them.)
(As a side note, I'm still shocked Morgan and Wong undermined Carter's repeated "no" in order to secretly film Frohike's death scene in Musings of a Cigarette Smoking Man, post here. They don't know what happened to the vanished footage, here... but in my opinion, CC won't tell them. I don't blame him.)
I write this not to point fingers or belittle credibility, only to remark that there is an insular quality to Glen Morgan and James Wong which disconnected them from the main thrust. (Darin Morgan played into this a little, too.) Despite writing a potential spark between the characters in Tooms, neither picked up on Carter's end goal and kept floating new sexual interests Mulder's or Scully's way. The disconnect in Season 4 was already present from the beginning, and further marked by messy canonical dates, a sole interest in their creative ideas, and a focus on Glen Morgan's love story written through Mulder/Riedel.
For further proof, we look to one of the official guidebooks--
The Complete X-Files:
Glen Morgan would later tell Entertainment Weekly [note: quote above] that Amanda Pays' appearance was no accident--the network was mulling replacing Gillian Anderson with a new actress.
However, I find the section discussing GA's pregnancy more
compelling--
As the producers struggled, often around the clock, to keep The X-Files up and running, a real-life drama would soon rock their world. Gillian Anderson had fallen in love with the show's assistant art director Clyde Klotz, and had become pregnant halfway through that crucial first season. Glen Morgan remembers hearing the news: "I was at home, and my ex-wife comes in and says, 'Gillian's on the phone.' I go, 'Who?' She goes, 'That girl who's the actress in your show.' I knew something was up, and she finally says, 'I'm pregnant,' and started crying," Morgan remembers, adding he advised the young actress, "'Don't tell anyone. Let Jim and I figure out what to do.' But she let the cat out of the bag, and Chris was upset, and the studio was upset." [...]
Chris Carter was shaken by the news and with good reason--he had put his own career on the line to cast Gillian as Scully. But the synergy of The X-Files had become an unstoppable force, and the writing team brainstormed on how to turn this crisis into an opportunity. "Gillian Anderson's pregnancy forced the show to create a mythology that had to account for her absence," Frank Spotnitz explains. "So, that led to the introduction of Krycek as Mulder's temporary partner, and led to "Duane Barry," "One Breath," and "Ascension." It ended up being the best thing that ever happened to the series. This mythology really ended up running through the life of the series, all because Gillian was pregnant."
(Of note: again, we're given Glen Morgan's perspective on Chris Carter's thoughts; but we're also shown how tightly CC's reputation was tied up in Gillian Anderson's success: from the beginning, he'd nailed his credibility to executives and producers based . The writers turning bad into good likely saved his hide, too.)
Lastly, I have to return to my opening points: everyone talked about Carter negotiating with, going up against FOX for, and staking his reputation on Gillian Anderson-- repeatedly, in under a year. If it weren't for executive Peter Roth (who advocated for CC's vision early on and continually), The X-Files might have either ended before it started or looked differently today.
Therefore, why would CC threaten that goodwill for an actress who wasn't well received by his viewer base (and didn't really strike a chord with critics, either)? Why would he unsettle the "vision" he stuck so closely to, and kept recreating later on?
In summary, it's a he said (Morgan), they said (everyone else.)
CONCLUSION
I don't believe Glen Morgan was trying to deceive anyone, but wires will be crossed on a production of that scale. (Reminds me of the William adoption arc: the "hows", "when"s, "who"s, and "why"s all mixed up.)
Now.
Is the rumor (Chris Carter replacing Gillian Anderson) impossible? No.
Is the idea (Glen Morgan or others knew of this plan) impossible? No.
But is it provable? Not even provable-- is it proven? No.
Granted, there might be a direct quote from interested parties which changes everything. But as of yet, there is only speculation.
tl;dr: Phoebe Green was created to cause friction in the MSR dynamic, ala Diana Fowley. There's no substantive report or proof pointing to Amanda Pays replacing Gillian Anderson (aside from Glen Morgan, who has a history of not quite understanding CC's intended goals.)