What do you mean by change factions? There are different answers based on exactly what you mean.

had the cup Units, uninstalled it, and added the rhs now we fight americans, but my mission giver is gone and when recruiting troops they dont show up anywhere, I know if I just add cup units again it will be fixed, but would like to change my faction if that makes sense, thanks

If you change major mods, such as integrated sides, you need to start a new campaign as it will otherwise not work.

CUP is not integrated into the mission yet and thus shouldn't have such an effect unless you edited the code to integrate it.

With it being RHS, make sure you have USAF, AFRF and GREF as all three are REQUIRED for the mission to function properly.

Oh, thanks for the last tip, didn't knew i need the three of them, thanks, also that makes my faction disappearance issue resolved I guess, thanks a lot <3

No problem, any time!