Neighbor kids

A

About a year ago a new family moved in with 3 kids. The boy is 4, one girl is 7 and the other girl is 9. I have a 5 year old daughter and over the last few months they have started playing with each other. About two weeks ago a new boy move in, he's about 9. Well over the last couple days the family with 3 kids and the new boy started playing together. Every time my daughter goes to play with them they completely ignore her even after she asks if she can play with them. One time when she asked if she can come in their yard to play the 4 year old boy said "you can go play in your yard."😭

I'm so devastated because this has led my daughter into tears and not only do I not know what to say to her except I'm sorry they aren't being very nice, I also don't know if I can do anything to help. Should I go over and ask the kids myself if she can play with them, should I talk to the mom about it or do I just let this happen? It breaks my heart seeing this happen to my daughter. She's always nice to them and always shared her toys when they came over in our yard to play.

I would appreciate any advice and sorry this is so long.

---My other question is, every time they see her with something they want to play with they come over and play with it. As soon as she starts to play with them with it they leave. Should I continue to let this happen or not allow them to play with it. I don't want to be rude or discourage them to have a friendship but they seem to be using her for her stuff.