Just curious what they really need to know? Guess it depends on how old they are.
My kids are elementary age, and they wanted practicality. Where are we gonna sleep? When am I gonna see mom? When am I gonna see dad? What about my stuff?
I think the biggest thing is to let them know that everything is going to be okay. I NEVER lie to my kids, but I let them know when I'm struggling, that things are tough, but I'm strong, they are strong, and for anything thrown our way, we are gonna handle it.
I saw a poster once who mentioned that maybe during school is better so their life still has some routine and normalcy. And it gives them a chance to get out of the house and NOT worry about things, which they shouldn't be any way..
Whatever changes are happening in the marriage and in the family structure, keep them updated and informed, but above all reassure them that things will be okay..