So I live with my husband and two daughters. One is his from a previous relationship and one is mine from a previous relationship. I am wondering if there is a way that he can legally adopt my daughter as his own, since her biological father isn't around and has never been. I do not know where he or any of his family lives, any phone numbers or anything and I have tried multiple times to contact him but nothing has come of it. So can my husband adopt her without her bio dads consent? Or what do I do?

Yes and no. The court will have specific rules for attempting to contact the bio dad. It will cost a lot more, if the bio dad can not be located.

You will need an attorney for this, since the procedure will be complicated

You will need an attorney for this. It is not a DYI kind of project.

Yes, the biological father will need to be contacted and will need to relinquish his rights. Just because he is not exercising his rights doesn't mean that he doesn't still have them.

The courts will require that you, at least, make an attempt to get the bio father's consent. That's one reason you need an attorney, to make sure that the court will approve your attempts. If you satisfy the court that you have tried and could not contact him for consent. it is likely the petition will be granted.

But why stop there? Why are you asking about adopting HIS daughter? How do you think she will feel if her dad adopts her step sister, but you don't adopt her?