My aunt M was holding A when MIL arrived. MIL swooped in like some kind of predatory bird and grabbed him. MIL hugged and kissed on him for a bit, then decided to hand A back to my aunt so she could help set up for the party. As MIL leaned over, she stopped midway, pulled back and started the "you want to go with so and so routine"? Really, it's "Let's show so and so who you like better." This went on for a minute before I told MIL to hand him over.
MIL gave A a birthday card. Just as we were getting ready to open gifts she pulls me aside and says, "Card Secreto!" WTF? So, I open the card and there's $100 bill. Why a secret and from who? SIL because she might get jealous. Wouldn't be an issue if MIL didn't play favorites.
MIL completely ignored her other grandchildren at the party. She didn't once hug, kiss, hold, or say hello to the other three. When she talks about A she seriously breaks into tears over how much he loves her. Biznitch is flucking crazy, and would loving nothing more than for her grandsons to think of her as their mom.
There was one other offender, and this time it was our neighbor. She pulled the "Who do you like better?" on my mom. It's bad enough she had to deal with that schit from MIL, but now the neighbor? I don't think so.
A had a cold but he was a trooper. The birthday party was a lot of fun and the cake I made turned out better than I hoped.
MIL is thrilled you're joining the family.