How can a girl act regarding her participation with her father's family in their innovated (bid'ah) occasions and her feigning prayer with them, while fearing being influenced by their actions, without informing them that they are Sunnis?

A Muslim must not attend places of innovation (bid'ah) and evil (munkarat) unless for a valid reason such as enjoining good and forbidding evil. This is based on the Almighty's saying: "And when you see those who engage in [offensive] discourse concerning Our verses, then turn away from them until they enter into another conversation. And if Satan should cause you to forget, then do not remain after the remembrance with the wrongdoing people" (Quran 6:68). And the Prophet, peace and blessings be upon him, said: "Whoever believes in Allah and the Last Day, let him not sit at a table where alcohol is served." If a family fears harm from speaking the truth or condemning falsehood, they should seek a way to leave that country. Indeed, migration from places of disobedience and innovation is a religious requirement.