No, absolutely not. Your stepmother does not have the right to take away the rights of you or your uncle. If we talk about the legal form, then the provisions are like this -
If the property belongs to the grandfather, then the grandchildren have full rights over it, even the parents cannot take it away. If the property belongs to the father, then the father can divide it among the children according to his wish, but the father cannot be forced. At present, along with the son, the daughter also has full rights on the property of the parents, which the law provides to them. That is, you can be sure that your property right cannot be denied.
As far as the property papers are lost, it is also not a matter of great concern, you will get the original copy of the document from the concerned registered office of the area in which your property is located, it is quite a simple process. For this, if you want, you can get it done yourself or through an agent. You and your father's presence will be mandatory at the time of collecting the documents.
Let's talk last about the decision, although there is also a system of civil court for such matters, my first advice is that if we settle the family matters by mutual agreement, then the decision will also be right and the relationship will also be maintained for the future because the relationship The role of property is much more than wealth and money. Still, if the situation gets out of hand, seek legal help and claim your rights.