If you take a logbook avatar then take the shield off of it, then that avatar will have all of its supports available (you still have to build the support level) for the path you are playing. I've used it to fix the problem with Fates not having enough women to get all of the children characters.
Edit: Having two avatars can cause issues, specifically a bug where your avatar is swapped with the secondary one. The only fix I've found is to restore from a backup. The bug only ever occurred once for me.
Sounds very risky