I have been with Apple for a while... well until 2014 when the iPhone 6 came out, I ditched Apple and moved to Android. Android is fun, but because it is more open, you try and do things and it doesnt quite play ball. Now with the iPhone 7 coming out I am being tempted back after a few year break!
Re this problem. If you are not too concerned about the billing side, I was sure that iTunes allows up to 5 devices? So can you not create a generic iTunes account with its own billing details, call it "family account" or something, then subscribe to iTunes match through it? Then to give other family members access, just log in to this new iTunes family account on your device and authorise their device (this will include apps though aswell - but as a benefit it will include movies and TV). They should be able to access your iTunes match content I am sure?
When I come back to Apple fully, I might test this theory. But like many others, this doesn't solve your billing issues. A solution here could be to set up a separate family top up card and use that? It prevents the kids from paying for expensive things and you can top it up now and again. Or as you are the sole controller of that pre-paid card, you can see the transactions going through and then reduce their pocket money?! :-) or get them to pay you in cash. My 6 year old isn't quite into this stuff yet, but I am sure I will learn a lot more about this kind of problem when she is old enough.
Does anyone know if this approach would work?
Something else also worth considering, and I do not know that much about the family sharing thing by Apple, and that is, what happens to the content you purchase in all of your Apple accounts? Keeping it all in one place might be a good idea, so that you can hand down your logins to the younger generation and keep all of the music in one place and in one huge master music, video and app account.