Sadly, because the Housing system is a Warbound system, I don’t think it’d be possible to have it be specific to the WoW accounts.
They would have to untie it from the warbound system, and make it character specific. Which would drastically increase the server space/processing they would need drastically.
A player like me, with over 20+ alts, would then be possibly taking up over 20+ plots across the neighborhoods. Which wouldn’t be fair at all for many players. As they might love the plot I have on an alt I rarely play, but because its still an active account and character… I’d have that plot.
That, or degrade the current Warbound system from being the entire Bnet account to just the specific WoW accounts. Which, I’m sorry, but I am definitely not for.
You may be able to create a ticket with Blizzard, and see if they would be willing to help you and your family split the old Family shared Bnet account into seperate accounts while keeping the WoW licenses and characters history. But, no gaurantees there.