My birth parents did not attend the funeral of my parents? Now they want a relationship with me?

I would have to say that you should go with what your heart tells you to do. If your birth parents never came around when you were coming up, and now only want a relationship because of money involved, then one would wonder what would you have to gain from them? Obtain a lawyer. You don't need the drama that might come with what they might bring to the table. Good luck!