Issues with Apple Music Family Sharing

I have an Apple Music Family Plan ($17.99AUD) per month for myself, my wife and my son. Seemed the sensible way to go vs 3 x $11.99AUD. However I am finding that the Apple Music Family Plan seems to have issues and wondering if others have found similar and ideally found a way around the problem.

We each have our own iCloud account and my wife and son use the same account for access to iTunes / App Store etc – i.e. their setup is the "preferred" / default model that Apple assumes when setting up a new device.

For a number of reasons (not the least of which being that Apple won't let me change my iTunes / App Store account to be the same as my iCloud account) I have different iCloud and iTunes / App Store accounts.

Family sharing is setup on my iCloud account with my wife and my son as Family Members. The sharing setup says that all Family members can share purchases (with the purchase account noted in the system as my iTunes / App store account which is separate to the iCloud account) and can charge new purchases to my credit card. Family members purchasing apps or music etc all works with no issue and the purchases are noted on their account as being by them and my credit card is charged. Exactly what is expected.

With my iTunes / App Store account I have purchased the Apple Music Family Plan, which I understand should mean that all family members get access to Apple Music. This works sometimes and sometimes doesn't. For both my son and my wife every few days I need to remove them from "the family" and re-add them and once this is done they can access Apple Music again. Real pain in the derriere.

Generally the remove and re-add is all fine however recently I was advised by Apple that my wife had to wait 54 days to re-join the family music plan vs with my son there has never been any issues with re-adding him. I managed to get around things for my wife by adding her back "into the family" via iCloud family setup on my Mac (which iOS would not let me do), but who knows what will happen next time. All in all a very frustrating ongoing pain.

So has anyone else had the issue with a user needing to be repeatedly removed then re-added to the Apple Family for them to be able to access Apple Music? If you have, and ideally also have found a way around it that would be great since the "Genius" folks at the Apple Store were no help. Generally Genius support has been great but not this time.

Also wondering as I have been typing this - if I let Apple Music lapse and instead take up an Apple Music family plan under my iCloud account will it then keep working? Will I lose access to albums I have added in Apple Music and have to do them all over again (assume yes I will).

Final question - wondering if Apple can successfully merge my accounts - I have a few historic email addresses linked to my iTunes account including some I can no longer access since I no longer work with that company. Had heard that trying to merge accounts could actually stuff things up. Any experience?

Thanks for any and all help.
Andrew