My mamani wants to sell her house (lower portion 5 marla) need advise

My mamu(late) had a house in coala center saddar bazar rawalpindi, it was alloted to him after partition and registry was transferred to him in 1964, the allotment was made in such a way that only the lower portion was alloted to him and the upper portion was alloted to someone else beside he gave it on rent to a person who later on did not pay any rent and forcefully occupied the house and is still living in it, my mamu fought 9 cases against him and won all but fail to getthe possession of the house. Unfortunately he died in 70s he had one daughter and one son and wife left as the legal hire of the property for which the succession certificate was issued, the son had a divorce with no children and daughter unmarried, unfortunately the son also died with only two legal hire mother(my mumani) and sister for which succession certificate is prepared. Now my mumani wants to sell that house and now she had applied for noc from the cantonment board now they say that there is a lease on house. Please guide us 1. Whether an noc is needed or not? 2. What is lease? After how many years it is applied on a residential 5 marla house?? 3. How can we know that there really is a lease on house? How much is the lease? 4. Can she sell without noc? 5. Can she sell without paying for the lease? 6. What are the consequences if sold without getting noc and without paying lease?? 7. How much is the market value of the house?? Please guide us . Thanks

Please consult with a good lawyer in rawalpindi.