This is a feature I've had in mind to build myself and has been on my back burner to-do list for years. I was actually just getting started on it when Covid hit and had to totally switch gears to other projects. Maybe I'll get back to it by fall.
My plan is to make a page that lists all the kids currently checked in, so a nursery working can quickly tap on a kid's name, then they get a list of pre-written text message options (things like, "Junior really misses you. Please return to the nursery at your earliest convenience." and "Junior is doing well. Enjoy the service." for new parents). Tapping on one of those would send it to the parents. It would run a SProc that creates the communication. Ideally, we'd also have a way for any message replies to appear on that screen for the nursery worker, and have a way for them to send a message back as well, but I'm not sure how that part would work or how important it would be.