Sale of jointly owned under construction propety

Dear Sir, I invested in a flat in 2014, the payment was construction based. The sale deed agreement on my name only. I kept paying the installments at regular intervals until 80 % construction was over in Dec 2017 (and 80 %Payment was done ) Thenafter, I decided to add my father, mother, brother and sister as joint applicants. Next month ( Jan 2019) , the remaining 20% payment is due when the possession will also be given. But Now, we want to transfer the nomination of the property to a new buyer via entering into a tripartite agreement bw the buyer, builder and us. Till now I have paid around 50 lakhs to the builder as 80 % of the total consideration value. The new buyer will pay us around 95 lakhs. My query is 1)if it is possible to accept the cheque for the entire 95 lacs on my mother's name alone OR is it that since I paid all the installments from my A/C , only I can take the cheque on my name? 2)In case we can accept the cheque on my mother's name alone, what will be her tax liability on the amount received by her. Will the entire 95 lacs be taxable in her hands or only the capital gain calculated after indexation? Regds