Teaching sign language to toddlers

Hey y’all I’m a daycare teacher to 18 month to 2 year old children, all but two of the kids in my class don’t really talk. I was talking with one of the other girls I work with and we were talking about possibly teaching the kids a bit of sign language. I mainly want to teacher them thank you, please, sorry, no thank you and you’re welcome. And she was talking about teaching them the alphabet in sign language but since they aren’t going to be going around saying the alphabet, I didn’t think that would be something good to do. Any thoughts on this? I don’t want teaching them certain things to prevent them from

actually saying them when they do start talking more