Partition of Undivided share of land

We are two brothers & two sisters. Our parents are alive. My father had purchased, on his own earnings, a property in my mother’s name 17 years back. Subsequently my mother transferred the whole land via gift deed to me and my brother. It was properly registered as 2 gift settlement deeds of ½ undivided shares each - one document was registered in my name and another in my brother’s name. The land was not physically partitioned when the gift deeds were executed. Both the documents shows the whole piece of land and states each can enjoy ½ undivided share. There was no any NOC obtained from my sisters at the time of executing the gift deed. Basis my share and using my gift deed, I had taken a bank loan and constructed a house in the whole piece of land where all were living together. After 2 years of construction, due to work, I had to move to abroad / different part of the city and my brother was living in that house for last 15 years. Now I and my brother would like to partition the land equally as individual shares so that we both (and our children in future) will have the liberty to do whatever we want with their respective shares without any dependency. Though I have funded and constructed the house I and my parents are OK for my brother to demolish the existing house. Leaving my piece of land, either he can build a house in his 1/2 share of land or he can sell his piece of land as he wish. Our parents also feel that we should settle this property without any ambiguity between me and my brother. Another information is that my father has gifted another piece of self-earned land as gift deed to my 2 sisters where they didn’t take NOC from me or my brother. While our gift deeds were registered my sister’s gift deeds were not registered. Questions: 1.What is the simplest option I and my brother have to get partitioned the land as individual shares? 2.As NOC was not obtained from my sisters while executing the gift deed, can my 2 sisters claim their share now legally?