1. You can get it mentioned in the said settlement deed as to who will hold the original registered deed and all link deeds,
2. You can not restrain them in selling their share of the property by keeping the original deeds. The sale can be conducted based on the certified copies also,
3. had it been a dwelling house, it was mandatory on their part to offer the said share to you first for sale at the rate they ware being offered. Since it is land, you can not restrain them in selling their said share,
4. You can get the clause mentioned in the settlement deed that before selling their share of the property bto a third party, they should first offer it to you at the same price they were offered by third parties.