Buying % of multi-unit from nonprofit

[Kate C.]

Hello, My father has vested 60% of a multi-unit to his nonprofit. 40 % is owned by his two kids (my brother and I own 20% each).  Does anyone have advice on purchasing a percentage of the building back from the nonprofit? He is getting older, and we would like to support the mission of the nonprofit but also think over time decision-making for the building would be easier, over time if we were majority owners of the building. Any general advice or experiences with something similar?