In Law Venting... fml

ok so we recently got in to a bigger house because our baby came in June, we purposefully added a room so family can come and be comfortable. when we moved in this Aug, we immediately invited my family for Thanksgiving and his for xmas... everyone said yes. we planned for 6 kids and 6 additional adults, not something that is like fucking overnight to prepare for. we bought more towels, sheets, beds, toys, raquets, etc. so Thanksgiving went off amazing and everyone had so much fun here and we did too. fast forward to today, when i text his mom and sister to see what days they were gonna be here and they come back with, huh?! his sister makes a lame excuse about her 7yo having made plans with a friend, having meetings about the finishes on her new house and something about not wanting the kids to think santa forgot them because she didnt want to wake up here xmas morning... but yet somehow santa can miraculously find his way to her moms house but not here?! wtf?! we scheduled vacation to be here, got gifts for the kids to open here and totally planned for them to come. god i swear shes so self centered i cant even...