Transfer/Consolidate iTunes

[slowdude]

Dear all, appreciate your advice.

Current:
PC User account A with iTunes account A with iPhone A,
PC User account B with iTunes account B with iPhone B.

Want to be:
PC user account A with iTunes account A with iPhone A, and
PC user account A with iTunes account B with iPhone B.

This is so that I can turn on wifi on my iPhones and my PC and have my iPhones auto-sync over wifi while I sleep.
And I don't have to switch PC user accounts.

Any advice on what I need to do. I don't have problems with the music as I have the original files for all the iPhones. I'm more worried about the game/user data on each iPhone which I cannot lose.

Appreciate your advice.
Thanks.