I need some advice. My future mother-in-law wanted to have an engagement party as a way for mine and my fiance's families to get aquainted. So only immediate family and friends were to be invited. One distant cousin- who has 9 siblings- was sent an invitation by mistake. How do I now fix?? Should I invite the other 9 and their spouses, or explain to her it was sent accidentally and my future-in-law's intentions?