When is a person co-located?
Some people simultaneously upkeep lives in two or more realities. While they are walking and breathing and eating here, they are also living lives similarly elsewhere. It's a very rare phenomena in the community, and not limited to Multiples.
(In my experience, it actually isn't all that rare. I would say that at least in my subtype, that it tends to involve two souls in the body here, one of which is "native" and one of which was placed there at birth or in early childhood. It is rarely viewed as multiplicity, and can be seen as common in some offline communities.
In these cases, the "other" body may also be asleep for extended time periods. This is one way of allowing an individual to focus more on one life at a given time. There are also ways of maintaining a type of "autopilot" in one body or the other.)-Blades