What is this celtic or gaelic symbol for fatehr and son?

My father has just recently ped away. I am looking to get a tattoo in memory of him. An idea i had was to get the symbol for father,a nd the symbold for son; and somehow link them together. Or if father and son was one symbol just use that. I am not sure if there is a celtic or gaelic symbol for what i want. If anyoen knows please tell me what you no, or if you no who to contact or where i could possibly get the information needed