There's a passage in Marina and Lee that mentions Oswald's disappointment with Fidel to the point where Lee was no longer interested in naming the expected new baby Fidel, which was what Lee wanted to name the baby (if it was a boy) before he left for MC.
Yes, good memory. I had forgotten about that.
Here's the account from the book. This is before he went to MC:
"Despite the harmony that presently prevailed between them, there was an occasional sign that it was not a case of two minds with but a single thought. They had always agreed that their next child, a boy, was to be named "David Lee." But for some time Lee had been turning another name over in his mind, and he cautiously broached it to Marina. He told her, stealing up a little on the subject, that he thought it might be a nice touch to call their new baby "Fidel."
Marina "reasserted herself in all her old magnificient asperity. "There is no Fidel and there will be no Fidel in out family."
However, later, after he returned from Mexico City, he told her: "Ah, they're such terrible bureaucrats that nothing came of it after all"....He was especially vociferous about the Cubans--"the same kind of bureaucrats as in Russia. No point going there......" Indeed, Lee's disenchantment with Castro and Cuba was complete. He never again talked about "Uncle Fidel", nor sang the song "Viva Fidel", as he used to do, nor used the alias "Hidell."
And, to your point, as Marina was preparing to give birth: "They had already talked about a name. If it was a boy, he was to be David Lee (no more "Fidel"), and Lee had promised that in the choice of a girl's name he wouldn't interfere.