This is kind of another 'take' on the poly discussions. As with all multiple partner relations, whether a dom OR a sub can successfully have more than one partner depends on all the people involved.

Communications between all the legs, whether a Vee or a Triad (flexing my small poly vocabulary) or interlocking sets, is important.

I think there can't be too much communication.

I also think the involved parties all must remain confident in themselves and of their relative roles.

I think I may be guilty of inadequately communicating sometimes... but circumstances can become "extenuating" as they say.