Quote -
The problem is that any rotation of the tongue1 actor causes the same rotation of the jawLower. Apart from this being totally contrary to real annatomy, it also means that the tongue1 effectively can not be posed. The problem is not with the parenting, it is a problem with the JPs in the jawLower actor. The solution is quite simple. Delete the JP channels in the jawLower that have tongue1 as 'otherActor', namely:

twistZ tongue1_twistz
jointY tongue1_jointy
jointX tongue1_jointx
smoothScaleZ tongue1_smooZ

I'm a bit baffled by this. Unless I have tomatoes on my eyes (as we say where I come from), these seem like perfectly normal 'mirrors' of a child's JP channels to me. The only explanation I have is that because there are no JPs set up between the head and lower jaw, but the lower jaw is set to bend, Poser takes whatever JP channels it can find.

Anyway, I've set bend = 0 for the lower jaw and kept those channels in for now. That seems to have fixed the problem. I don't see any reason why the jaw actors should bent, seeing as they only contain the teeth and parts of the gums, but as long as the extra channels do no harm, I'll keep them in until I'm further along with the rigging of these parts.

While I was at it, I've also made the translation channels for the tongue1 actor visible. I'm not completely sure yet whether I'll use ztran or xrot for pushing the tongue forward in the end, but for now, people can use the z- and y- translations for positioning it the way they need it.

-- I'm not mad at you, just Westphalian.