I suggest you do some reading here and find out what the terms are that are used first. Then you can create your own. It is very difficult to talk to other poly people if you are using a different language however so some tolerance might be in order if you are hoping to be a part of a larger community.
For instance, "sister wives" is a polygamy term, not a poly term. In poly we have "metamours." This term is used for both males and females who are the other partner of our partner. Also, the term "primary" is given for the partner of someone who is of most importance, rather than "Alpha."
I can appreciate that you don't like the terms. Some don't some do... but they are known and understood... there is a whole section on definitions and terms in the stickies, or you could do a tag search for "primary," "secondary," "metamours," "hierarchy," "prescriptive," "descriptive," anything that takes an interest. Oh, "unicorn" is another as that seems to be what you are looking for.
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