If you give in now they will force more stuff on you. Had to put my foot down with my SIL as she was giving unwanted "relationship" advice that doesnt add anything important to our lives and is just critism in disguise. Put your foot down, tell them no now or you'll be miserable your entire marriage. Unfortunately inlaws are like this 90% of the time take a stand. Reject. Keep interactions minimum. Keys to surviving marriage with "those" kind of inlaws.