Long terms capital gains tax exemption for new property over old property

I sold a property and booked LTCG of 35 lakhs, my wife owns a separate property in her name and if she sells it now it would have LTCG of 35 lakhs. we want to buy a new house which is priced at 70 lakh. Qs. 1. Can we both claim section 54F (or some other section) to get LTCG exemption by selling our own individual houses to buy a joint new property? Is it so even if the property is underscontruction and may take 3-4 years to get built/registered in our name? 2. Can I buy the new house only in my name if the new property is underconstruction and may take say 4 years to build/possession/registration? One opinion I got was that the date of registration is considered for buying new house and since the new property is to be purchased within 1-2 years of selling old property I cannot claim 54f. Is that true? 3. Can we buy (and so book for now) the new house in my wife's name who eventually intends to sell the present property and use 54F to show that she is buying the other property and pay some token amout for booking in her name? Till when does she need to sell the property to avail 54F.