Oh dear. Well, it's hard to say without knowing more details and of course, we cannot diagnose on here. That being said, it sure does seem out of the blue, inexplicable and like unpredictable behavior. It is also very odd that she ignored your other daughter's birthday, and all birthdays for three years, then shows up for the 16th birthday - not only that, but with (in my opinion) an over the top gift from someone who had blocked you from their life for years?

I think you need to trust your own gut reaction on this one. If you say she's manipulative and a narcissist, trust your own reactions and conclusions. Only you know the full history with this woman, and all her behaviors and actions.

At the very least, it's a head scratcher and is certainly suspect in my honest opinion. I would be wary of it too.

And you have to ask yourself, what kind of person blocks out family members simply for a disagreement? That is certainly unstable behavior and is not normal behavior. She certainly has something, but I cannot say what.