I know someone who reverted to shia Islam from salafism and he is living under taqqiya from his parents because If they know he is shia they are going to get really mad and probably disown him too but he wants to tell them the truth one day and I would like to know the ways to bring it up to his parents slowly so they accept him as a shia

What I would humbly suggest is to protect his relationship with his family and do ehsaan, show them love and best of akhlaq instead of revealing the truth for now