1971 -Doom is still training at Karma-taj. The F4 have their powers. To get funding they work for SHIELD still, but they aren't happy about it. though after a few years they get fed up with the bullshit.
They start the Future Foundation, which is an advance science research and education non profit, and keep to private life. Franklin is born in 79. Doom is kicked out of Karam-taj in 81. He goes back to Latveria which is part of the Socialist Republic of Romania at the time. Doom fashions his first armor suit. Then he ejects the communists and declares Latveria and independent kingdom, and him self sovereign. Latveria is now the crossroads of the west, shield, hydra, and the communist. Doom's plots to exploit all this sometimes result get the F4 involved. One particular incident in 84 has a pregnant sue in Latveria. Where Doom uses magic to help deliver valeria. Doom becomes Valeria's godfather.
doom establishes diplomatic relations with wakand, befriends the king. is the first nation in history to do this since wakanda was discovered. though this doesn't do much, since Latveria is so closed up it self.
in 2000 Valeria runs away to Latveria to live with Doom. franklin frequently leaves the earth to handle extra dimension and cosmic threats. He has Galactus like a pet. The F4 and Franklin were off in space, trying to settle the Kree/Nova Corps conflict during the invasion of new york by Loki. the sokovian incident caused dust cloud to fall on Latveria and sent large numbers of Sokovian refugees to Latveria. Putting the Avengers on Doom's list.
most of the back story can be filled in on tie in comics, Agents of Shield, etc. Then we just have the present day and old F4 in a future movie.
maybe a netflix series. set during the 70s when they were super powered family adventurers working for shield.