cannot sync ipod touch

I have an Apple ID and my husband also has his own ID. Somehow this is causing a problem, my husband used to just use my ID and itunes but when he bought a Macbook for some reason he decided to create his own ID. Now when he tries to sync new music to his iPod Touch using his Mac the device is recognized but just won't sync, however it managed to wipe off 18Gb of music from the iPod so not a happy chappie. I want him to stop using his own ID and go back to mine, would that work? I have tried to sync his iPod using iTunes on my Windows PC but I don't know how to find out which account it is attached to, mine or his? In the olden days you could go to a the Apple site and check out every Apple device you owned but that has been chopped. He has a lot of his own new music which he has converted to MP3 and put into iTunes so that part is working. What a muddle!!

By the way, all our computers have the latest version of iTunes.