"encouraging W to find another partner so long as said partner is approved"
"W says M has actually given permission for everything and anything so long as it's never talked about between them"
So... it's a DADT relationship, except that when telling does happen, then M has veto power?
Yeah, that really IS confusing, and would be whether this was a D/s relationship or not. Honestly, I think you could either go for it or not go for it and still be considered an ethical person, since you've tried to follow their rules. I mean, if you've been attempting to get in contact with M, then at least he's aware of you. But I wouldn't pursue it, myself. Too much weirdness. Either wait until W is willing to resolve the issue his/herself (why can't he/she just request that M contact you? is their power exchange really that total?), or find someone with a less schizophrenic set of rules.
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.