How to add a property to a company in the backend

Hi
Now a company owner can add a property, thats great.
The property will belong to that company.
But, how do I assign an already existing property to an already existing company from backend?

Exampel as follow:
Company A, B and C are existing but with no properties.
Property 1, 2, and 3 are existing property but not assigned to any company.
Now I would like that property 1 should belong to company A.
How can I do this in backend? I can´t find anything about this in the forum or in the manual.

Hope I´m clear with my question.

Hi,
Company admin can create property, but the property must be assigned to agent of that company. So you only can assign the property to agent of company, not specific company.
Thanks
Dam