Hope I can help, please be aware this is not 100% flushed out and may change slightly.
The owners field is a vector of size 1 right now (hashset/vec, makes no diff really). It can be an outright majority (> 50%) but may be more granular (from your next point.
instead of just the owners field we can have granular controls, so owners could be Ford, Tesla etc. with sub organisations/managers in the granular controls fields.
So the post says the machinery is there, this is the Vec, however its limited to 1 entry right now. The part that prevents us (apart from time, this usual) is the messaging of signature gathering (this is the part to flesh out). It is not difficult though and there are two pretty clear options IMO
The network holds signatures to alter an MD until there are “enough” to make the alteration. (State on network is not always good though).
Clients pass round the MD item to be signed and append sigs to this until there are enough. (not so nice and bad clients may consume and not send this, although we can use a broadcast/collect system to subvert that).
We have plenty of options though and data chains will allow the ability to have data act as though the signatures were part of the MD, just as they were with the SD, but validated on the chain, not internal to the data.
I hope this helps, as usual time is our killer, the team wont get to involved in the convo I think as they are against the cosh with the current releases, but I hope this helps at least. I can try and explain more, but feel the team also need the discussions internally as well if you see what I mean. So shout if this misses your point chap, I will try and add more to this suggested route.