Oh no, you communicate with all of them for sure.
Basically, I have no boundaries to how far I explore my relationship with someone else. If it starts interfering with another relationship, it can cause a break up in the problematic relationship. For example, I hang out with Melissa (fake name) two-three times a week. If I start a relationship with someone else, and I'm only hanging out with Melissa once a week now, it can cause conflict as it is obviously interfering with the relationship. The relationship can drop to "secondary" status, or we can just break it off, as a new primary relationship is emerging. Quite similar to being monogamous, and you start liking someone else, you break off the current relationship.
Also, I have rules to never deliberately interfere with another's relationship. Melissa for example can not whine to hang out with me Friday night if I have a date planned with someone else. By doing so, she's deliberately attempting to end the date, or if she a calls repeteatedly during a date. Or anything of the like. You either do not interfere or improve the relationships I have with others. Same rules apply for any new partner.
There are many other rules too. Of course, it seems complicated, but it's rather natural for me now.