My FSIL told me this yesterday and I thought it was good advice. Her DH and her got married almost 5 years ago. She only gave plus one's to long term relationships. however her then FMIL through a fit because one of her DH's brother had been dating a girl for about a month and they were supposedly really serious about each other. She caved because this MIL insisted! When the the time came to take the picture of his side of the family MIL also pushed this girl into the family picture. Now 5 years later none of them, including MIL or BIL can even remember the girls name. So be weary of this, you don't want this to happen to you.