BoB concept goes completely out of the window when young dependants are involved.
Don't get me wrong, I have a 60L ready to go in the cupboard, but can't think of a scenario where staying put with a local plan in place isn't the better idea.
Discussion
I hear you. Good on you for having a 60L at the ready!
Ok, 56L. One of the below with two 4L detachable side pockets. The sides make great first aid kits.
https://www.fjallraven.com/us/en-us/bags-gear/backpacks-bags/trekking-backpacks/singi-48
That looks sick 🫡
House fire. Your world is likely to come to an end before the world does. Pack up comfort bags for them for stressful circumstances. In times of crisis they will want familiar things they enjoy.