I would say that defining "person" is not too important to saying if a tulpa is a separate person or not. At least, not to me. I think defining person is unnecessary because we are not questioning if the tulpa is a person, but if it is a separate person or not. I think we are all accepting they are a person. So, by saying that tulpas and host are persons, we can skip over what makes them a person. It is more about what makes them the same separate persons. What makes us separate from other people in general, is useful to know. I would say memories and experience are very large things. I would also say fight or flight responses are important, because at some point it is the body reacting alone, without permission from the person, it is like your heart beating, something uncontrollable, but that behavior affects both the host and the tulpa in ways it would not affect separate people. There is only one stream of consciousness, for a host and a tulpa, which separate people do not have, as in parallel processing is not real, and I think that is important to defining if they are separate or not.