My husband and I, newlyweds though almost 50, have been invited to my cousin's wedding out of state. My cousin is the same age as my son (28), though I've never seen (my cousin) or have had any contact with him whatsoever, until now. The invitation arrived without an RSVP card; there is only an address on the outside of the envelope from the addressee. What are my obligations to this invite, if any?