Multiple Apple IDs and purchases

So here's my situation, I'd be grateful if anyone can offer any suggestions.

We have 3 different iPhones being used in the family (mine, my wife's, and my son's). My account is the primary for our family, and through that we all use an iCloud plan to back up photos and other stuff. My wife has made iTunes music purchases on HER account that we wishes to share with my son, but since I'm the primary I don't think she can do that.

My understanding is that all shared items originate from a single account where those items are purchased.

We could conceivably make her the primary, but then we would have to set up our iCloud plan through her account. Would there be a risk in losing any backed-up info when we set up a new iCloud plan and started using that?

I haven't been able to find a good solution to this, I would appreciate any suggestions. Thanks!