Hi Rainbow,
I felt so happy for you reading about your session!! I agree that you and your t seem very compatible -- much more than you and your previous t. It's huge too that you said you know things won't change with the t relationship even when you or she is gone. That shows you have learned how to "hold on" to the good feeling of attachment. It does sound like you are developing a secure attachment to her!
I'm so sorry, though, that your grandkids pay more attention to their other grandma. That's got to really hurt!

Kids don't usually think deeply enough to realize they are favoring one relative over the other. They just respond. Could it be that they see the other grandma more often, and maybe that is why they seem to feel more comfortable with her? Regardless of why, don't lose heart! It takes time and repeated contact to develop relationships. Are there some things you and your grandkids could do to build your relationship, even though it is long distance? Kids are really into texting. Could you text them at times?? Also, kids usually love to talk about their hobbies and other things they are interested in. Asking questions about their activities might open up more communication. I'm not saying that you don't do that already -- just throwing out ideas.
I know you well enough to know you're an intelligent, empathetic, special person. I'll bet if your grandkids get to know you better, they'll come to value you as well!