Ownership Of House

My mom bought a house 8 years ago which was under co ownership of brother and sister, we paid full amount and had the agreement signed. We even checked in regional register office if there was any pending cases on the property 2 weeks before registration, at that time it was clear. Later we receive a notification regarding dispute on ownership. One co owner recently divorced, his wife filled a petition saying that they've used her dowry in construction of house. Now we also filled a case against it saying my mom unemployed widow paid full amount and deserve complete ownership of the property. The advocate my mom hired did nothing other than filling the case, now our original document is stuck at court. It's been 8 years. Kindly advice necessary steps