A practitioner asks: “I have gathered that we have one higher self that manages all of our incarnations, because the Pleiadians, through Barbara Marciniak, once suggested that is the situation, but that may not be correct.” What can Creator tell us?

That is correct. Each and every soul is unique and each and every soul extension intended to incarnate in the physical realm is unique. Because the higher self is a component of that being, simply as another level of consciousness comprising that being as a whole, the two go together and stay together. Whether in a series of lifetimes or branching along the way to allow multiple incarnations, all will be managed by that individual soul's higher self. This is not difficult because the higher self, being within the divine realm, has light being capabilities so that level of multitasking is no problem. If you think about this from a metaphysical perspective, if everything is happening in the Now, such that all other lifetimes are actually occurring largely in parallel and simultaneously, there is already quite an extensive multitasking underway on the part of higher selves as well as the portions of consciousness within the physical extensions.