-OK heres what you do, I just did some testing...
-It sounds to me like your using inbetween blend shapes to produce a kindof start to finish, but inbetweens go in the order thay where made they don't actualy blend the motion, but heres how you can. ..(("someone who understands scripts or plugin could probably use this to write a button to do this and have it end up with one slider..."))
-Say you have a target object w/ 3 copys adjusted to create a hoping non linear motion when you select them in order and apply and in-between blend, but you get a blenshape control that at 33.3333 go's to the first blend position exactly from there to the second blends exact position at 66.6666 then on to the final blend position, in a from a to b to c fashion...
-When you want to use the combination of the blends to create and offset...
So, take the and I apply what would be the first blend shape in the equation above and make it just a regular blend, THEN the second shape in the equation above apply it as a blend shape to the shape you aplied as a blend shape then the same to that.
EX: you have A-(the original Target) D-(final resting shape) B & C-(as the shapes that will offset it)
Select B then shift select A create a default blend shape then select C and shift select B and create a default blendshape then select D and shift select C and create one more default blendshape.
Now on from 1 key all the blendshapes at 0.000 then at frame 100 "just so you can see the effect" and key all the blend shapes at 1. Press play, You can add an attribute or make a custom view with a slider and create a set-driven key slider from 0 to 1 so you only have to deal with one slider...
-have fun...
sid
sid69graphic@yahoo.com
"-if it wasn't for 'Y' we wouldn't be?"