Transfer of Property.

Mr. D owns a land. He dies without executing a will. Post death his land is inherited by his sons. The land is equally divided among 5 sons in a mutual agreement and no paperwork is done. This implies that there is no deed defining the share of 5 sons and their rights in the property. The elsdest son Mr. K possesses a deed which was executed when D acquired the land. A copy of such deed was given to rest four. On a piece of paper it the share of land was agreed upon and signed by the brothers. Now one of the brothers Mr. M wants to sell his share of land. On consulting a legal practioner Mr. M is advised that he needs the signature of all the other 4 brothers (in case any brother isn't alive , signatures of their legal heirs is reuired). Besides he is advised that the legal heirs of Mr. M ( I.e. a son and two daughters) should relinquish their rights in the property in a relinquishment deed). And only after satisfying these conditions the property can be sold. Please guide if the legal practioner is correct. Who actually have the rights in the property ? what is the best possible way to sell this property ? Is it possible to reverse mortgage the said property ?