Legal Rights of property belongs to uncle

Dear Sir, I with my parents and sisters reside in a house for more than 50 years which belongs to my uncle now sold by his sons 4 years ago to another person. The details of the house and my family is below :- 1. My father's second elder brother brought a house 60 years ago when the family was joint. 2. Now 30 years ago his sons told us that the house belongs to their father and we have no legal rights on this house and should evict. 3. We reside that house with my father's first elder brother and all other family members shifted to another location more that 40 years ago. 4. My father's second elder bother in whose name the house is got expired more than 10 years ago. 5. Now his sons sold the house 4 years ago to another person who claimed that as my father's name not in any deed so I can not claim any rights on this house. 6. He is ready to provide a token of space on this house to reside but as per his will. 7. Neither my cousins brothers nor the person purchased the house taken any NOC or consent for such purchase/sale. 8. The person purchased the house only declare newspaper notice for any objection of anybody having any interest or claims in the house which generally overlooked by everyone. 9. My cousin brothers never took any legal action to evict from the property. Now my questions are :- 1. Whether there is any legal side in my favor. 2. Is there any legal side where I can claim that I am the first person to purchase the house sold by my cousin brothers. 3. Is there any legal side where I can claim having legal rights for residing that house for more than 50 years. 4. I with my parents/sisters having voter id card, ration card, aadhaar card, passport, bank accounts, school certificates, etc. on this address issued by appropriate authority. 5. My father and one of my unmarried sister is orthopaedically handicapped. 6. If I claimed to purchase the house now whether the person is bound to sell to me, if yes, then at what price? 7. Request detail legal steps to be taken to claim for the property. Please help me. Thanking You Yours Faithfully, ALOKE KR PAL