I'm a bit confused about this whole wali business.... I've heard that a woman needs to have one of her mahrams or a wali present when she signs the marriage contract, but who can be the wali? I've heard from some that it needs to be one of the mahrams, but how does that work for converts? None of her relatives are muslims! And how does it work if she has her parents' consent (even if they're not muslims), but they cannot be present for various reasons, and she has no appointed wali? Will the marriage be invalid??