Just a little worried

I am currently pregnant with my first child. And I am married to my husband who has three other children. We are co-parenting with their mothers (there are two). Well what I'm worried about is they are going to think we don't care about them as much and the new baby, or that we are replacing them and I don't ever want them to feel that way. We love them with all our hearts. So any other mothers or fathers here with any advice for me.