1. Yes, Mr. RJ and Mr. MJ can stake claim to the property now.
2. As per amendment to the Hindu Succession Act, 1956 in 2005, Mrs. P.T also was entitled to equal share in the ancestral property, since there's no registered partition deed.
3. If it were to be ancestral property and when we consider amendment to the Hindu Succession Act, 1956, in 2005, since the partition deed was not registered at that time, it's open for review anytime and the limitation period of 12 years may not be considered.
4. If Mr. RJ and/or Mr. MJ stake claim, you may also be treated as one of the parties.
5. It's advisable to show the property papers to a Legal Professional and elicit opinion before proceeding further.