I love a spread finding challenge
I looked in the spread index in the spreads area of the forum and they are all really love triangle type spreads.
Tarot Orat does good poly spreads, here is her
triad spread you could use that and add to it! or custom make one.
A bit like Ravenest's
what I want in the relationship
what my partner wants in the relationship
what I want in the third person
what my partner wants in the third person
what will the third person want?
what will the third person be like?
where will we meet them / how to find them?
if you want to know exactly about the person in a predictive way, adapting this
soul mate spread:
1 - What will the third person be like? (Court Card)
2 - In what situation will I/ we meet them? (Minor)
3 - How to approach/charm the third person? (Ace)
4 - Advice card (Major)