It depends on what terms the loans were made, what your minutes or resolutions said about them at the time, and what your articles say.
Did you extend your leases, if so then the majority of that loan has been repaid by the conversion of the asset to a longer lease for an individual, as the value has been taken out. The remainder would reflect the right to sell other leases ground rent income and any development rights.
Sale of the flat and the share in the company can be a way to deal with the loan but in the absence of context, as above, they could argue that they can have their cake and eat it.
Pull out the above documents and see.
Based on the information posted, I offer my thoughts.Any action you then take is your liability. While commending individual effort, there is no substitute for a thorough review of documents and facts by paid for professional advisers