Like others have said, for some people this is where the pansexual label comes into play, but honestly, who cares? If someone identifies as bi and is attracted to trans* folks, then really, they're just seeing the person for the identity that person is presenting and embracing and that's all to the good for everyone involved, in my opinion. Many trans people just want to be recognized and seen as the gender they identify as and are transitioning to. A trans* man is a man and a trans* woman is a woman, so why shouldn't a bisexual who is attracted to men and women be attracted to them? I wouldn't challenge the identity of a lesbian or a straight male who is attracted to a trans* woman. She's a woman, they're attracted to women, so what's the problem? Likewise a straight woman or gay man attracted to a trans*man is just a person attracted to men being attracted to a man so there's no identity crisis I see here. Bisexuals attracted to trans* folks is the same. The only time I think it's called into question is if someone is attracted to a trans* person BECAUSE they are trans, which could, theoretically, cause new conflicts, for example, if the trans* person just wants to be seen as a man or a woman, not something in between or something else entirely. Some may not want the fact that they are trans to be a focus of the attraction of their partner, others may not mind or may like it. Really, It comes down to whatever works for the people involved and whatever they want to call it that makes them happy and comfortable.