Introducing Metamours

Back in the summer, my husband (32M) and I (31F) decided to open up our relationship, eventually focusing on a polyamorous approach. I have two lovers that I've seen a couple times and plan to continue seeing (both 31M). My husband and I have very open communication and the lovers are aware of this. Everyone is open to meeting. I would like to facilitate this eventually as it will make certain things less awkward - e.g. if one of them comes over to our apartment to visit one day. One of the lovers is also interested in a threesome with my husband. Interested in any tips or advice from people who have set up meetings like this before. I'm not concerned about jealousy from my husband as it has yet to come up. He experiences a lot of compersion and we have a very trusting relationship. I am concerned about jealousy from one of the lovers.

FYI I try to have a nonhierarchical approach to poly as much as possible, however I am married and am not at the point with either of these two men to call them a 'partner'.

Thanks for your help!