So this is my first post and may not be as well articulated as some. However, I am still a little confused with some statements. Clearly you want to make sure that neither you nor any of your family are perceived as polyamorous. Yet your tone is that you are exploring this site as a member of your family. That family mindset seems very similar to the mindset of the "poly" community where relationships are among committed people.
Admittedly, most poly relationships seem to involve sex and I think you are trying to make it extremely clear that is not the case in your family. The exception being your husband because it is just as clear he is polyamorous in the complete sense because he is having sex with all of the wives. Or at least I assume he is, but maybe he is not and only has sex with the one "legal" wife.
I may be wrong, and this is not meant to be a judgement, but you appear to value rules above all else. Not rules established by someone else but rules that flow from your internal values. I would guess that you view external rules more as restrictions to your freedom rather than a community standard. Of course the danger of community standards is that we are individuals in our personal lives and to comply with community standards we must give up and even betray who we are. Never a good thing. However, without community standards we cease to be a community, a country, etc. The trick in life is how to tolerate deviations from the standards with losing the community.
When you posted your first post you had a very clear vision of your community standards of an appropriate welcome. But none else did. Likewise, the existing members of this community also have a clear vision of how this community operates. They responded from their perspective. The problem was that neither understood the other. Misunderstandings must be clarified or relationships don't work. Isn't that really a fundamental premise of making a polyamorous relationship work?
What we have is an opportunity learn about how to make relationships work. This is what I seem to be learning polyamory is all about. Could you have reacted differently from the way you did? Yes! Could the others have reacted differently to your response than they did? Yes again. And if and when we stop to think about how we could have reacted differently, we will learn more about ourselves than about anything else.
It is a hard hard lesson to learn but Steven Covey is right on when he says;
"We perceive the world not as it is, but as we are."