Don't keep score, try to go with the flow, don't make comparisons.
IF you feel neglected, keep the topic to YOUR NEEDS without bringing the other person up AT ALL in the conversation. That helps you identify your needs in your relationship individually. Not a matter of keeping the social aspect of the relationships separate-but it helps keep the RESPONSIBILITY for each duo separate which is critical.
Read up on "polymath" (galagirl has links for that on this board somewhere, so you could pm her).
In a group of three people (I am in a V also by the way)-
there are 3 duo's you and your partner, you and your metamour, your partner and your metamour.
In each case-the two people who are part of the duo need to take responsibility for fulfilling the needs of THAT duo relationship-the third party needs to NOT be held liable for neglect within a duo of which they are not part.
So-for example, if Maca feels he isn't getting enough time with me-it's not "you spend more time with GG than me".
It's "I need more time with you" then we negotiate what amount of time our relationship needs in order for both is and my needs to be met. It's not GG's responsibility and therefore he isn't the "problem" and shouldn't be used as such or blamed for me not giving Maca enough time (which is what the first sentence does).