Ask in this order,

• What is your thoughts on dreams?

• Do you think dreams can look into other realities?
  (can be rephrased as "...Can look into other worlds?)

• Do you know of the dream mother?

• (ask one additional question about the dream mother, continuing off their initial answer)

• Do you believe dreams can see into the future, even if rarely?

And then rate the score:

• +1 point for positive

• -1 for negative

• +0 for neutral

If the score is at least 3, they are a possible dream walker.