Perhaps we are missing something here. You might also want to speak with a knowledgeable Buddhist, and explain to him that as eldest son, you may be duty bound; and that in doing so, you either are or are contemplating becoming Catholic, (and without being rude about it, expressing it in a way that your belief system is moving from Buddhism to Catholicism). You might ask if anyone else would perform the necessary ceremonies, and also if it would be offensive to them if you did so, considering your intent to become, or having become Catholic.
There are two sides to the coin.
While there are things the Church and Buddhism share in common, the gap between the two is far different from the gap between Catholic Christians and those of other denominations. I can understand some of your hesitancy and questions. God bless you on your faith journey, and with the question you post herein.