Backing up 2 different iPhones to one computer

From my reading here, I understand that is fine to backup two different iPhones to the same computer. She has a iPhone 10 and I have a iPhone 11 but she now has a new 12 on order. She is very concerned that she might lose her pictures or music in the process. I prefer computer backups as compared to the cloud and I do not wish to mix our music between the phones so therefore I suppose that I shouldn't sync her phone to my iTunes. To my point, if we are going to back them up to the same computer, should I use her iTunes login for her phone and my login for my phone or does it make a difference? Any other advice would be welcomed.