IMO if you are in any kind of poly relationship and a parent/prospective parent, you are welcome here. Likewise those with previous experience, as long as they are not here to condemn.
I'm not sure there are paramaters to poly. I can only speak for what defines my own relationship. I am in a polyanderous, polygynous relationship. In laymens terms, I am in a 'love based relationship' with two men who are with me and me alone. Well, at this point 'with' is a relative term because my ex dh and I are no longer physically intimate or anything of the kind. We still live in the same house, we still take care of each others non-sexual needs, we are co-parents of our children, and he is the godfather to my youngest dd and takes care of her as well as his own two bio children when I get a chance to work or need a break... My primary relationship, my beloved Viper, and I are intimate on more than just the physical level. That said, we are co parenting as a whole, and neither of them is in any way intimate with anyone else, and neither am I.