My Granddad died recently at the age of 102 and the funeral was this week. DM and her siblings let all the grandchildren know that the great-grandchildren were very welcome at the funeral but not expected and that it was up to us, as parents, to decide whether or not to bring them.
The great-grandchildren range in age from 14yo to 3mo. The older kids all came as did the baby which was no problem. My cousin decided that her 2yo and 4yo would never sit still so didn't bring them.
We discussed it with our boys and they were all keen to go. DS1 (11yo) and DS2 (8yo) are both generally well behaved so I was happy they should come. DS3 is 5yo and can be a menace so I was less sure about taking him but it was a 4hr drive from home and so we'd have to leave him overnight by himself with the PILs. The PILs were happy to do that but DS3 really didn't want to be left so we agreed to take him. Beforehand we set out clear expectations for him and also agreed that if he didn't cope with sitting still then DH would just take him out and go for a walk.
My DB and SIL also decided to bring their kids. My nephew (10yo) was a delight as always. However my niece (5yo) was, in my opinion, a badly behaved brat. DB and family arrived late (they delayed the coffin to let them into the chapel first) because DN refused to get dressed and then DN proceeded to demonstrate her gymnastics skills at the front of the chapel through the entire service! DB and SIL made a few half hearted attempts to get her to sit down but basically just let her carry on doing cartwheels and twirling around waving a scarf over her head.
AIBU to think that if she couldn't sit at least reasonably still then DN should have been taken out of the service?
FWIW this is fairly standard behaviour for DN and DB and SIL could easily have left her at home. They only had a 45min drive to get to the funeral which started at 11am and was on a day they both normally work so have routine childcare from 8am-6pm.