Ok, I think I worked out a couple of things.. hope it'll help
- the hands are sticking to determined rigid bodies (or collision boxes if you will) and unfortunately the dick is not one of them.
- the rigid bodies have spaces between them so if the hand is too near to 2 collision boxes will try to clip to both of them causing clipping and trembling.
- Wierdly the torso bends in a direction inverted to the extension or height of the arm, in other words, the further away you try to stick the hand, the more the shoulder will go backward turning the model towards the camera. This limits the extent of the limb and during the motion can surpass it causing trembling or pose deformation.
Regarding the pose:
first a couple of quick suggestion:
- always put the hands in a neutral position (U,I,O,P keys) or just stick them to the chest, you will pose them for last.
- move the man away before trying to pose the doll, better if already near the final position to avoid unwanted contacts that will screw the pose.
The pose itself:
Starting from standard SDT pose and side view:
- raise her butt untill she spread legs to the desired (possible) extent, this is model dependent, so some models won't spread legs.
- move the butt forward a bit to exagerate the result (will be needed in the next step)
- now take her head and drag the model up (not too much), the legs will straighten and close a bit.
- Take the man move his head backward and alligne him in position a bit lower her crotch, if you did it right he should fit between her legs w/o clipping.
- Take her butt and drag it towards the dick until they clip, the rest of the body should stay still. (don't try to do that by aiming the dick, is a loss of time, if you have troubles try by moving the man's butt).
- Now that the link is done, set the bodies in the preferred position by adjusting the backhead.
- Finally set the hands in position remembering the suggestions above, so try to always keep the arm somewhat angled.
you are ready to go, now try the auto movement.
If it trembles it means that some limbs are over extended, try adjusting the pose working on hands, butt or head.
Took a lot to write, takes 2 mins to do, good luck! and enjoy