We're dealing with various family care issues so there are a couple of things. I'm surprised you don't have a will already with even one property under your belt. Is there a property management company taking care of these rentals? If not, it is going to be harder for the person who inherits it to deal with them in the moment.
I have an old will that I need to update. Yeah, these things need updating as life is full of changes. I think (it's been a while since I've looked at it) I just say real estate goes to my husband.... who wasn't my husband when I wrote the will. Then if he's not alive, a list of relatives get it. I still need to update that thing.
What about the children? That has very little to do with RE. You should have some paperwork or something regarding who should be your children's guardian and the "who" may change as they age and the "who"'s ability to care for kids change too.
Because of the family issues we are dealing with, the living trust thing did not work in our case. Problem is you have to have an active account with assets in the trust. When my husband took over the care of his mother, there was this trust but nothing was in it. He's had to deal with so many issues with her assets because none of them were in the living trust.