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I think you'll have to check up on A often to make sure he is still feeling "okay" (if not great) about these poly relationships. I don't know that any polyamorous (or monogamous, for that matter) relationship can ever work out so that no one gets hurt. Wouldn't it be nice if such could be the way it is. Happily ever after and all that. The truth is, people get hurt feelings, have arguments, and have to renegotiate the situation so that everyone can live with it.
Of course, that's not at all the same thing as saying that it can't work at all. Sure it *can*
work, in some cases, with sufficient honesty, communication, patience, and diplomacy. I'm just saying almost every worthwhile relationship involves some sacrifices, regardless of whether it's a poly relationship.
Make sure you have M's wholehearted consent before pursuing anything too heavy with him. Of course, before he can consent, he'll have to know what he's consenting to, so at some point you'll have to let him know what's going on, with respect to both your feelings and A's.
I guess I'm curious about what ground rules you and A negotiated, but it's up to you how much you want to share of that kind of detail. As long as it works for all involved parties, then all is well.
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