People do not account for the weird ass situational dynamics the Fresh-Out-Of-The-Portal-Ford got dropped into. And I'm not talking about Mabel and Dipper staying at the Shack, or the Shack being a tourist attraction itself.
I would like to, at some point, explore the idea of what the hell Ford would do if Stan was out of commission when he got back.
Not dead, to be clear. Just. Unconscious. Sick or something. Maybe he hit his head during the Portal's activation and is out for the count.
Because I think without Stan mediating, Ford would have VERY LITTLE idea what the hell is going on.
Ford gets back to his home dimension, and there are two children (twins, he can tell right off the bat. Chubby cheeked and they look familiar, painfully like the twins in the picture Ford carries in his pocket) and another man that looks like a large hairless gopher. The twins are Mabel and Dipper, and the man is Soos.
All together they drive off the federal agents that were apparently after his brother, for some reason And manage to settle the sick/injured/otherwise unconscious Stan up in the Shack, sleeping peacefully.
At some point during all this another girl shows up brandishing an axe at Ford and being threatening despite the fact she can't be more than fifteen.
Himself, (traveled in the multiverse for 30 years and has no concept of contect for this world, arguably the most responsible. Cannot cook)
Mabel and Dipper (twelve, staying over in Gravity Falls for the summer at their parents wishes, full of questions, cannot cook.)
Soos (Twenty One and very nice, unknown relation but knows the answer every question regarding the Shack or Stans medical care, including medication he has to take which no one else knew about. Can cook)
And Wendy (fifteen, suspicious and protective, unknown relation. Second in terms of knowing things about Stan. Can cook a little)
And Ford takes all of this information, mulls it over, does the math, thinks it through and decides "Ah. Stan has had children since I've been gone. Checks out."
(He probably gains the nerve to ask Wendy where her mother is, thinking Stan's...wife? Is probably out of town or something, but Wendy shoots him a mean look and says "she's dead, actually." And Ford panics so hard about the social blunder he never asks another question)
So for. However long it takes Stan to wake up, Ford is operating on the idea that, in the three decades he's been gone, Stan has built a family (tragic, about his wife. When he asks Mabel though she mentions a divorce, so maybe its not so tragic-?) And a business (which all the kids (soos included) demand stays running even while Stan is recovering because Stan would hate to see it closed) and a happy life.
So, Ford decides he must be a Good Uncle, and steps up. He's proud of Stan, even if his twin did technically steal his identity. He's still mad, a little, but Ford's heart is very quickly melted by Stan's kids.
And they ARE Stan's kids. Ford can absolutely tell.
Mabel and Dipper, despite being a neice and nephew, remind Ford of Stan a lot. The adventures, their personalities, their...inclination towards committing crime with very little hesitation
Seriously Stan, what are you teaching your children?
Soos is, of course, Soos, who is very concerned about Stan's safety and also the rest of the kids, and he takes to his temporary job as head of the Mystery Shack like a duck to water. He reminds Ford of a younger Stanley, eager to please and strong willed, determined to get things done.
Wendy is a wild card in that Ford doesn’t know exactly how best to connect with her, but Soos assures him thats just how Wendy is. Wendy has all the snark and the spark that Stan had in their youth, and Ford sees that right off the bat (its funny because she swings a bat at him at least once)
All in all, by the time Stan is awake again and back in the game, Ford is undeniably smitten with this ragtag bunch of kids Stan has. He's proud of how Stan raised them, proud of Stan for being the father they didn't get.
Stan, fresh out of a sickness/concussion/whatever based coma, looks his brother dead in the eye and says "Stanford. What the fuck are you talking about?"