Creating a Family Account using an Apple ID that nobody uses as their Login

They won't unless they also have computer accounts and your music is partly from CDs.

Use the Finder to sync your iPhone, iPad, or iPod with your computer - Use the Finder to sync your iPhone, iPad, or iPod touch with your Mac - Apple Support

If you use iCloud or other services like Apple Music to keep your content up to date across all of your devices, some syncing features through the Finder might be turned off.

What can you sync with the Finder:

Albums, songs, playlists, movies, TV shows, podcasts, books, and audiobooks.

Photos and videos.

Contacts and calendars.

The AOL labeled Apple account (I'll call it the AOL account for simplicity but I do not mean any account you have with AOL itself) is only being used as a source of funds for the Family Sharing group, but it is your main account that is actually part of the group. To do what you wish you would need to have both your personal account and the AOL labeled account as family members. If you wish for the AOL account to also manage the family you would need to disband your current family and start a new one from the AOL labeled account. This would probably done most easily from a computer where you could have two users on the computer, one for each account. You would only need to use the AOL tagged computer account when you want to manage the family or funds. You'd use your other account as you usually do, but since there can only be one Organizer, the AOL account would be the Organizer.Organizer. It is not easy to use two accounts with Apple mobile devices, and certainly not in the way you wish.

So ideally I should have some piece of tech with the AOL account as the primary account? I've an old iPad that I could repurpose in that case, would that work to administer the account?

I realise that in order to access my iTunes Match i'll still have to have the AOL account listed for purchases on my devices won't I?

Some piece of tech yes. I only said a computer because you have have multiple Apple Accounts signed in as different users on a computer. Apple mobile devices can only really accommodate a single user account except for a few very specific and limited purposes. You shouldn't need to do a lot in managing the account apart from making sure any payment methods are kept updated.

Note that if you are using iTunes Match, I don't believe that is included in Family Sharing. So if you have a CD with music you have uploaded to Match, I don't think others will see that CD. They will see items you have purchased from Apple, but that is independent of Match. I don't use Match myself but I am pretty sure that will be limited to you.

Correct about iTunes Match so hopefully if I leave my iPhone, iPad (under "Media & Purchases") and computer with the AOL login for the AOL account that uses Match I should be ok. The only downside is my wife and kids will no longer have access to my rather eclectic iTunes library, correct?