1st - "conservative Mormon sites" will take a FAR dimmer view of his research than anyone here, LOL. The offshoot groups such as the Reorganized Church of Jesus Christ of Latter Day Saints or the Fundamentalist Church of Jesus Christ of Latter Day Saints are where you would start, and neither has anything to do with the actual Church of Jesus Christ of Latter Day Saints. Just sayin', lol.
Technically speaking, all of those terms fit with Polyamory. The "split" is in those groups that are usually associated with the term. Many of the "polygamist" groups - noteably those two mentioned above - participate in practices that many Poly people would consider abhorent; arranged marriages, underage marriages, sometimes incest.
So really - as much as I'll get flamed for saying it - Polygamist groups very much fall under "our" umbrella, by definition.