How would the details of the dd’s death change anything at all?
In some ways, not at all - she needed support from her family and they withheld it.
In other ways, there's a difference between how you might expect a wider family to respond to the loss of a much-wanted pregnancy, and the loss of, let's say, a baby or child. When the OP says "her daughter" it could mean either.
But fundamentally, it sounds as though the circumstances around the loss of her daughter were fraught and that certain family members let her down very badly.
Also, I would find it difficult to get excited about a second wedding to a second husband! There comes a point when I think it's okay to NOT indulge somebody, and this might be it, everything else aside.
OP, I'm very sorry for your loss, and that your family hasn't been supportive of you.