Honestly, I strongly believe that the way to beat jealousy and insecurity is NOT by insisting that everyone must love each other equally, which isn't generally how people work and is unpredictable at best, but rather by working on becoming more secure and better at identifying and dealing with jealousy. That brequires a ton of communication, introspection, more communication, trust-building, etc. It's hard work, but shortcuts will just backfire (as in "why am I *still* miserable and freaking out when we set this up so that we could avoid ever feeling these things??").
Great resources here: http://www.morethantwo.com/jealousy-insecurity.html
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.