Sale of Settlement Deed before demise of Settlor and his wife

Case Background: My Father in law has executed a settlement deed for a flat in Chennai in favour of my wife in 2009 mentioning the clause subject to interest of him and mother in law being taken care of . The Exact wordings are Subject to the life interest and right of resiodence and Income of Settlor ( My father-inlaw) and Settlor's wife ( My mother in law) . He also has put a clause that if the settlee ( My wife) desires to sell the property, consent of settlor and his wife has to be taken . Issue in Hand : Now my father in law wants to sell of this property to external unrelated party , though the settlement deed is in vogue. My wife is perfectly OK with that. The question is Sale consideration should be in settlor's name or settlee's name? ( We do not prefer settlee i,e wife's name as we cannot explain capital gains at all. and the sale deed to new party will be executed between the settlor and new buyer or settlor, signed also by my wife as a setllee? The advise is urgently neded