Is receiving of cheque or receipt is important ?

Suppose i and my brothers together selling my land to a third party, now registry has been executed best on trust. It is written in the sale deed that we will handover the receipt of sale ,once we receive the money. I given them receipt without acknowledging about money receiving. Now they are not paying us our money. When i filled a case against them they have submitted the cheque of my name in court which is actually cleared by my father in joint account (me and my father). Now my question starts from here. My father and i have joint account. Now if the buyer handover the cheque to my father in name of mine, he can easily got cleared from joint bank account, although it has my name. Since my father is mentally sick, they used them to cheque got cashed and taken money from him, i was never been aware of that. So in real i got no money from them. My question , is it allowed to handover cheque to my father without my consent? is my receiving is not important? how can they claim the cheque my father has cashed was the money against land , it can be of any purpose. Also i have another question, if a person is minor through his matriculation certificate, he has no other certificate before that (like birth or anything). Now if someone claims that people use false information during matriculation to get govt. job, and say he is not minor will that be accepted.