Rather than make a discussion to sever relations with any family, would it not be better to just be you, go on the trip. remind them that you love them regardless, and let them react how ever they want to?
As people are thrown in to situations, their first reaction to change is to fight it, be angry with it, try to find someone to blame for it, after a while they realize fighting change is a waste of energy and they often start accepting the change for what is really is
