I’m working on an adaptation of the scene from the Vader comics where Vader finds out that Luke is his son. I’ve hired a voice actor so far, and am working on compiling footage that can realistically fit into ESB. My idea is that it’ll play out at the start of ESB, but end on Boba leaving Vader in silence. Then, either the end of ESB or the beginning of RotJ will show the scene with the flashbacks, cementing the previous reveal.
This is an excellent idea - having the comic book adaptation inserted into the movie. It makes it more clear later when Vader is talking to Sidious later on that he is deceiving him. Boba is also with an expanded role and screen time for a character that would in later movies and shows have his role expanded.
I would be hesitant using flashbacks. Flashbacks were not used thorough out the OT nor PT. Personally, I like the use of flashbacks, but it would stand out in a Star Wars movie. However, perhaps you could incorporate it in a way where it does not feel out of place. I am looking forward to what you accomplish with this.