The mark on her shoulder signifies that she is part of a wolf pack that has been run-out-of and kill off in Lousianna. We are talking about her direct descendants, but appearantly Hayely must have been hidden or taken away fairly yound (she has been saying her early life was pretty bad). If I remember correctly she was originally in Louisianna (meaning this DOESN'T need be the truth concerning the location or origin of her wolf tribe) to find information about this specific wolf pack with her "birth mark".
Maybe she is an old descendant of the Original Pack, if they exist in this TV universe. It may also be that women from this clan ALONE can bear children from Klaus and that is it...something unique to them only.
As for Tyler and the "helping the pack of wolves" deal... I think it's fake, I have one idea on this below. But, IF Tyler is helping out some wolf pack, it is more than likely unrelaed to Hayely's situation...
BTW, about the wolf that is gaurding Hayely... Is there anyway it could be in actuality Tyler? Either because Tyler likes her and wants to be protective or he is doing a favor for Klaus to get him to leave him be. but, there is one more (if it is Tyler) that eventually Tyler seeks revenge for his mother's death. It'd explain were in the hell he has been this whole time and also why Klaus suddenly picked up "guard duty" knowing his one hybrid had left. I guess if Tyler sticks around on TVD and the wolf is still around we'll have our answer. Otherwise, I'm hoping that it is actually an Original Pack member that ahs been drawn to the baby and is watching the situation.