Property cheating case

Hi, few months back we sold our ancestrtal property for 40 lacs - 30 Lacs in cheque and 10 lacs in cash. We are 4 brothers and each had a 1/4th share in this. The first 10 lacs were recd in cash and were handed over to the youngest brother and his family and they accepted it as their share. The rest was recd in cheque and was divided amongst the other 3. The youngest brother is now claiming they didnt receive anything and have filed a case. Because it was a family matter, no receipt was taken from the youngest brother. The youngest brothers family, and also some other independent persons are eye witnesses to the cash being paid to the youngest brother. How can we defend ourselves against this fradulent claim by the youngest brother given that there is no paper trail of the cash payment to him? Thanks