Even if you are not interested in non-monogamy relationship, the part about discussing feelings, setting up boundaries are very useful.
I feel like even monogamy couples should learn more about those, like, just because the other has free time doesn’t mean you are entitled to all their free time - people need time alone too.
Everything you know to know?
Everything You Knead To Know. There's lots of massages to give to multiple partners!
A great article for everyone. 
Even if you are not interested in non-monogamy relationship, the part about discussing feelings, setting up boundaries are very useful.
I feel like even monogamy couples should learn more about those, like, just because the other has free time doesn’t mean you are entitled to all their free time - people need time alone too.
Everything you know to know?
Everything You Knead To Know. There's lots of massages to give to multiple partners!