Okay here's my Thomas' crew headcanons so far:
Joe Bloggs and Tom Cobley are Thomas' original driver and fireman, the ones who came with him to Sodor in 1915. It was claimed they were sent there by "accident," when the truth is that Joe and Tom basically stole Thomas and ran so they wouldn't end up in the war effort, knowing it was likely they would never be able to return to England. The only people who know were the driver and fireman and the first Topham Hatt. Thomas never learned the truth until the night of Joe's retirement
Thomas' current driver and fireman are Robert "Bob" Bloggs and Terry Atkins. Bob became Thomas' driver after Joe's retirement; Terry became the fireman several years later
Bob married Alice Smith and they had one child, Margaret. She becomes Thomas' new driver after Bob's retirement. Because she's the third generation Bloggs to be Thomas' driver, she goes by Maggie Bloggs on the railway, even after she got married
Thomas thinks every driver he has is part of the Bloggs family. This is partially true, but he also applies this to relief drivers, which would not be true. He doesn't apply this to the firemen
The only time Joe was truly mad at Thomas was when Thomas broke his snowplow. Literally everything else was fine up until the moment Thomas refused to cooperate with the snowplow. Things got better though, after Thomas learned his lesson the very next day
Bob's very first run as the main driver for Thomas was the Down the Mine story. You know how well that went :P Bob got really stressed because it was literally his first day as Thomas' official driver and he already got trapped in a hole. The fireman had to console him
Bob thinks of Thomas as a cat passed down to him by his father. Which means that he would ride to hell with him, but he would also be constantly scolding him for his cheekiness. Terry teases Bob by calling him Thomas' second dad
The BWBA movie is basically where things come to a head. A strained marriage between Bob and Alice is what gets him to go along with Thomas' plan to travel around the world. Terry gets roped along too, but only because he didn't even realize what was happening. Terry admits his feelings for Bob. Bob realizes he's bisexual and also has feelings for Terry. Bob and Alice have a long-distance phone call and Alice admits she might be a lesbian. Bob and Terry kiss at some point. Bob and Alice remain friends. I realize that the "Jokingly shipping a pairing to actually shipping it" pipeline is real
If there was a Christmas special to be had, it would be Bob, Terry, and Alice getting together and figuring out how to break it to Maggie that 1) Bob and Alice are separated, 2) Alice is in love with a woman, and 3) Bob is in a relationship with his railway co-worker, and also that 4) this all happened while she was away at university. All I know is that the entire sequence of events is what happens when you invite an engine to the Christmas family gathering. Maggie is stunned, but chill about it. And then Joe Bloggs walks through the door