We hosted Thanksgiving this year. It was only DHs brother and his family, plus his Mom. 11 people total, not too bad! 
 

SD14 only made an appearance for food of course. Her cousins are 1 and 3 years younger. Not too much of an age gap though that you can't have conversation. DS3 had a blast! His "big cousins" played hide and seek, soccer, and construction trucks outside with him. He later said "I had so much fun today!". Brother in law asked "so I guess SD13 doesn't ever play with DS3?" He didn't seemed surprised. But didn't say it in a mean way either. Just very matter of fact. I said no she doesn't, but he doesn't know SD any other way, so it doesn't phase him. 
 

Later on DH said SD14 needed to come say bye. She went on a blame game of "no one wants to talk to me" so that's why I hid in my room. DH called bull on it. I just minded my own and went outside. 
 

I had zero interaction with SD14 the entire Thanksgiving. So did my DS3. We are getting ready for bed and She finally decides to finally speak. Almost 7:30 pm. Do you have a phone charger I can borrow?" I said "No, I don't sorry." She proceeded with she only needed it for ''a little while''. I said "you can try looking in the kitchen drawers for one." She responded with "no I already looked." 
 

I stopped responding. Like seriously??? You have ignored everyone the entire day, never uttered the word thank you, but get annoyed that I won't give you my only phone charger? I was flabbergasted. Looking back I wish I would have said that, but staying disengaged is the way to be and take the high road. What would you have said?