Capital gain

Hello, Pl. consider this case: Mr. A has given advances to buy a property to Mr. B in many installments starting from 2013 till 2016. Meanwhile without taking the possession of the property Mr. A is selling it to Mr. C in 2017. As per Income tax act it is transfer (since it is relinquishment of right) and there is long term capital gain. The property is sold by way of a tri party agreement in which A is nominator, B is owner and C is buyer. Now I have following questions: Whether the indexation will be done for all installments starting from 2013? Whether the buyer will deduct tax at source for the credit of owner or nominator? Pl. guide on the issue. Thank you in advance.