(((((hugs))))) Either ignore their idiotic protests or else tell them that if they want to host the celebration at their own homes then they can do that next year and they can set the rules.
As for easy child not wanting to pick up Katie and her family, I would DROWN her in guilt over all you must do, iwth the food, the cleaning, etc and how long it will take you to make the trips and the amt of gas it will take etc... Also I would say if it is half a block, sheand her crew should WALK except if the baby is sick. Otherwise, how are they getting their exercise to stay healthy? trust me, there would be so much of my schedule poured on that girl she would be BEGGING me to go pick up her sister. And yes, I HAVE done things I did NOT want to do for a holiday simply because my parents asked. It does not MATTER what they want, their house, they ask, they get.
