How do I convince my parents to attend a wedding without me?

We recently received an invitation to my cousin's wedding. We all umed I would be attending the wedding along with my parents (I'm 15), but after receiving the invitation we discovered I have been excluded from both the church and reception. My parents (especially my father) is very upset and refuses to attend the wedding without me. How do I get through to them that they should go to the wedding? I don't want my dad to miss out on his nephew's, hopefully only, wedding. I completely understand that is their wedding and they should have who they want in attendance on their big day. I do not want this to be a problem and cause a rift in an already unstable extended family.