Morkus from Orkus
Cambions are specifically demon and other(often human). I don't remember if the offspring of a devil and other had a specific name or not. I think it did, but can't remember it.This particular subject is ridiculous.
Few people say, "Hey, descendants, who wants ice cream?" (Although if I had kids, I might; I'm that kind of person.) Everybody who uses descendant understands that it means their children and grandchildren. In legal terms, it means children, grandchildren, and others in your direct bloodline
Tieflings are not the children of fiends; those would be cambions. Many are, however, descended from fiends, which means they could be the grandchild of one, or the child of a cambion.
But! There is absolutely no reason why you can't be a tiefling who is the direct descendant of a fiend and a mortal! Call yourself a cambion if you like, but as long as you only have tiefling abilities, you're fine. Just don't include a ridiculous tragic backstory or expect bennies because Grazzt's your daddy.