What is the ruling on saying "Lord, forgive me and my parents" while sitting between the two prostrations, and is this permissible?

You should adhere to the supplication reported from the Prophet, peace and blessings be upon him, between the two prostrations, such as "Rabbi ighfir li (O Lord, forgive me)" or "Allahumma ighfir li warhamni wajburni warfa'ni wahdini wa 'afini warzuqni (O Allah, forgive me, have mercy on me, mend my affairs, raise my status, guide me, grant me well-being, and provide for me)." It is permissible to add to this supplication, but it is better to stick to what has been reported and to make supplication for one's parents during prostration or before the taslim, as the Prophet, peace and blessings be upon him, said: "As for prostration, strive in supplication therein, for it is most likely that it will be answered for you."