Advice for land in the heart of rawalpindi city

My father shares an ancestral (inherited) land in the heart of rawalpindi city with his cousins and brothers etc. My father has a share of about 2 kanals where as the total piece of land is about 7 kanals. Only make shift stores / go-downs are present on the land whose rent are collected by my father's cousins. Some land (about 1 kanal) is free without boundary wall. Now the problem is that we want to sell our part but the other family members (father's cousins) are not interested to sell because they are getting rent from the land. When my father ask to demolish the make shift stores and sell the whole piece of land then they say that they will demolish when deal to sell is final but most of the buyers say to demolish every make shift construction before any deals. The value of land in that area is about 8 lacs per marla after making plots of 5-7 marlas. Please advise how we can sell our portion and deal with this situation. Also advice on below:

1. How can my father get the possession of his share i.E 2 kanals through legal process and how long it would take?
2. What will be the approx price if my father sell his ownership without possession and let the buyer take the possession himself?
3. Any other advice to get out of this situation.

Waiting for your replies / expert opinions.