After much consideration I decided to go to neither the ceremony nor the party. It is a difficult choice. On one hand is family unity. On the other hand is a very doubtful sacrament. I have messaged a few people and even priests on this issue but have received conflicting advice (similar to this thread). One says the new rites are valid and it's fine to go, another says it's most like not valid but to go for family unity. Others say not to go as to not cause scandal.

Personally I would rather not risk my soul on a doubtful sacrament (and i've seen strong information regarding the positive doubt on the new rites for ordination and consecration). Vatican II definitely appears to be a new religion, with a new mass and new sacraments...I have messaged the family members in question, but I hear they aren't happy with me.