Succession deed used for unlawful mutation

Ajay Naik was born in year 1930 at Altinho NorthGoa. He got married to Kaveri in year 1950. They registered their marriage at the Registrar office in Portuguese language. They got 3 sons namely Amit, Akash and Atish. (These 3 sons did not knew about their parent's marriage certificate, everyone else thought it was never registered). After few years, Ajay started working at some part of SouthGoa and started living there. There Ajay got in relation with another lady(Veena) and got 2 sons. He kept it secret for some years but his married wife(kaveri) and whole family understood it at some point. He managed to brought up both families. Veena lived with 2 sons at her house in SouthGoa. When Ajay retired, he lived with kaveri and 3 sons at his house in Altinho. He never brought Veena and 2 sons to his house in Altinho NorthGoa. Ajay looked-after the living, study and later jobs of those 2 sons, later they started earning good, became rich and lived happily with their mother in SouthGoa. Ajay died in year 2010 and Kaveri died in year 2015. Veena died in 2020. Amit, Akash and Atish registered deed of settlement between them and put shops and some businesses in the ancestral properties and enjoyed the possession. Then they initiated a inventory in civil court. Meanwhile, after many decades of birth, those 2 sons managed to register a succession deed of Late Ajay and Late Veena at Altinho, NorthGoa having false statements on it like 'they lived permanently in Altinho at Late Ajay's house' etc. And later made mutation and put their names in place of Ajay's name in form 1&14 of the ancestral properties at Altinho. Amit, Akash and Atish got to know this when they issued 1&14 for 'list of assets' for steps in the inventory and got stressed and helpless. Those 2 started disturbing them in their businesses because they thought that Late Ajay's 1st marriage never registered. Now Amit, Akash and Atish found their parents marriage certificate and those 2 sons stopped disturbing them in their businesses. How to remove their names from form 1&14 which they did by mutation from mamlatdar office? What should Amit, Akash and Atish do?