Oral Partition

I have two sisters and a brother. Father passed away in 2010. Mother is still alive.
My father partitioned his ancestral property in 1992 by oral partition and made memorandum on 20 rs stamp paper. They divide property in 4 parts. 1 for him, 1 for my mother, 1 for me and 1 for my brother. After my father's death his property divided in 5 parts. in this my sisters got equal parts. One of my sister is expired in 2018. Now my late sister's heirs have objecting the partition done by my father. They want to re partition done by my father in 1992. Other parts have been sold by my mother and brother. only my share is not sold. Also my late sister's heir also sold their share they got in father's share. Now they are threatening the purchasers of my property not to purchase. So my questions are:-

1. When my sister was alive, she was no problem with the partition.
2. Can It be re partition?
3. What about sold properly?
4. My father partitioned property as per the laws applicable in 1992. Now new laws will be applied?
5. For 27 years I have revenue record and paying taxes for it.
6. My another sister has no problem with that partition.
Please help me