In previous FMRTE, you could go to any club that has affiliations and change that specific one to anything you want. Change parent and feeders club to any of your choosing. I used it a lot and came to many crashes, but found a way to avoid any failures or crashes along the way. I don't how crashes are with this FMRTE...
The way: Change an existent affiliation, for instance Real Madrid has Sanse as feeder. Change Real Madrid to your club, Sanse to your desired feeder. Save the settings and save the game in FM. In FM, go back to Main Menu, and reload your save game. Everything should be correct and displayed correctly.
Good Luck until the add "+"