WALK-INS
The walk-in experience is considered a soul exchange which involves two souls in one physical body but not at the same time. This exchange is supposedly by agreement. One a soul enters the body while the original soul leaves. The second soul will then complete the life-cycle of the person.
The soul aspect that leaves is most often dysfunctional - working on lower emotional frequencies unable to tolerate the pain and suffering endured in the physical. It will leave - perhaps by death - accident most of the time at which time it will move to a higher level of itself - that which deals in a more functional manner allowing the soul to experience through new 'eyes' - a new emotional body.
One may perceive this as a a soul exchnage - but it is the same soul in different frequencies of experience.
The walk-in soul usually goes into metaphysical studies - healing and hleping others. It may bring prophecies - seen while in a Near Death Experience - when it is consciously aware of the other side - or higher frequencies of conscious thought.
Please remember that the concept of a walk-in exchange should not be confused with psychological disorders such multiple personality disorder.
WANDERERS
Wanderers are thought of as souls connected to another place - planet or realm - who have come here on a mission - after which they will return home.
Often they do not remember what that mission in.
Sometimes they feel it is to prepare humanity for coming change - perhaps a visit from ET's or moving into love and light, etc.
A wanderer who cannot find their mission will become depressed develop lower emotional frequencies - fear, panic and anxiety.
Again... it is important to determine if a mental illness if present and the person is not merely lost and searching for greater meaning to life in higher consciousness.