Is Sale Deed required if Registration happened?

I am a buyer and I have done my "Agreement to Sell" by paying 20% money on 17March, 2016 for a resale property in Kalyan, Maharashtra. There is a clause in "Agreement to Sell" that rest of the money will be paid by bank loan. I paid stamp duty and registration happened on the same day. This is something different from Delhi, where notorised 'biyana' happens in advance, bank sanctions loan on the same and Registration happens after full payment. At that time our broker didn't inform us about "Sale Deed". Property has two owners, both stays in different cities. One owner has a small baby and she don't want to travel but ready to sign some papers if i share through coureir. Moreover she has given POA to first owner but it is on a 50Rs stamp paper. Few questions: # is Sale Deed mondatory in my case? # Does she really have to come down to Mumbai to sign Sale Deed? # Is 50Rs POA valid in Maharashtra? # Can she sign POA or Sale Deed if i share through courier? # is there any alternative approch except Sale Deed? Below article say "Sale Deed is not required and they say, it is required if it is a resale property. I am really confused.