I have a two candle love spell I borrowed from one of Z. Budapest's books, where you identify one candle as the person the spell is done on behalf of, and the other as the target person they wish to attract (Note: this is never, ever, a specific person, as that would interfere with that person's free will, be unethical and backfire badly. Instead it is a collection of qualities, which can be written on the other candle with a pin or rose thorn). For a poly person, you could include candles to represent other partners in her or his configuration (or not) if they feel good about that, and if a focus of the spell is for the new person to be compatible with who is in her life currently. these candles could burn at the same time at a bit of a distance, but not be involved in other ways.
The spell basically works that you set the two taper candles at a distance from one another, identify them as what they represent, and then light them. You move them a little closer together and let them burn down for a couple of hours or more. The next night you move them closer, and let them burn down a little more, on the third night you move them right next to one another in the same holder and let them burn down until they burn out completely in a pool of intermingled wax. When you move the candles together, magically you are moving the person and their desired together, which will manifest in the real world. There's a bit more to it but you get the idea.