Sibling jealousy worry

whoknows

I'm due with my third child in February and I'm a little worried about my older children feeling jealous or replaced. When I had my second, my son was only 1 year old so he really didn't know what was going on and adjusted pretty well. But with my third coming in 10 weeks or less I've started worrying that my kids being older will have more feelings about it. My son is 5 and my daughter will be 4 right around the time baby is born. Anyone have any advice on how to help prepare them or handle it? They understand that there's a baby in my belly and seem excited so maybe it won't be a problem?