Multiple Apple IDs; only some used but need all for Family Sharing

My wife and I both have 2 Apple IDs (long story). We’ve been using our “old” IDs for iTunes purchases, etc. and our “new” IDs for iCloud, but this has become more and more awkward. With Family Sharing now, we’ve switched to using our “new” IDs for everything — but we don’t want to lose the legacy media (movies, TV shows) we purchased with the old IDs.

My only solution so far has been to create accounts on our MacBook for all four IDs and set them all to use Family Sharing. The content is all in iCloud, so I’m wondering if I can now delete the accounts on the MacBook for those old IDs without impacting Family Sharing and all that legacy content. I’ve tried logging into iCloud.com, but there’s no place there to access the relevant settings.

I’m about to try this — the accounts for the legacy IDs are just an iCloud login and Family Sharing config, nothing more. But I thought I’d ask to see if anyone has experience with this.

If we eventually just get rid of our MacBook, and we need to change any FS configuration, I suppose that’ll be a problem. But I don’t see that anytime soon on the horizon.