It might be worth getting in touch with the Ecological Land Co-operative.
https://ecologicalland.coop/
They purchase farmland for use as farming co-operatives.
They raise capital using 5-year Bonds backed by the value of the land they are going to purchase, using a very similar legal mechanic to a leveraged buy-out, but to a very different purpose.
The ownership of the land is put into a legal structure using a co-operative ownership model. That land is then leased to the farming co-op’s that work the land. The Farming Co-operative’s are the Worker-Members of the Land-Owning Co-operative, while the Bond-Holders are Investor-Members.
Once the Bonds are paid back, via the rents paid by the farming co-op’s, the Investor-Members will withdraw from the Land-Owning Co-operative, so the only members of the Land-Owning Co-op, will be the Worker-Members, who are the farming co-operatives that are owned by their workers.
In essence, it gets the farmworkers to own and control the legal shell, that owns and controls the legal shell that owns the land.
Via a two-stage ownership system, they own their own landlord.
In order to do the Bond Issues in the UK, the Ecological Land Co-op operates under the auspices of the FCA, which means keeping careful track of everything, including the Member Registers you were asking about.
They would have a lot of useful advice about how they did this, as well as advice about being compliant with the UK Financial Regulator’s requirements.
The organisation that worked on the Bond side of the legal details is Ethex:
https://www.ethex.org.uk/
They are always raising finance for community projects, CIC’s, as well as Co-op’s. They would be another source of good advice, as well as having contacts with all of their other successful past projects.