Grr, sodding blendshapes in Maya, forgot how to creat in-betweens so started playing about and wrote it down. Finding it really helpful nowdays im getting old...
"Adding in-between blendshapes
To create inbetween blendshapes for say opening an eyelid you'll want an in-between to get a nice slide over the eyeball instead of going through it,
this is because Maya will transition between the base and the blend through the shortest route.
Select your ending blendshape and then shift-select your Base object (that the blends will be applied to).
If its your first blendshape on this object you'll wanna go ''Create Deformers - Create Blendshape - Options', name the group of blendshapes under the
'Blendshape node', make sure envelope is 1, local origin and check topology (should all be Defaults anyway) and create.
If its not then go 'Edit Deformers - Blendshape - Add - Options and select 'Specify node' with the correct node selected and check topology. ('Add in-between
should NOT be checked at this point). Click 'Apply and close'.
You'll notice under 'Window - Animation Editors - Blendshape you'll have a new node you created and if you slide up, your object will transition
between your original object to the object you set as a blendshape.
To add a blendshape in-between the two states you created, create and mold the object for the in-between, select it, shift-select the base object
then select 'Edit Deformers - Blendshape - Add - Options', click 'specify node' (it tells Maya what node this will be placed under)
then select 'Add in-between target' and under the 'in-between weight' select something like 0.5, and under 'Target index' you need to count
what blendshape this will be placed on, for example if the in-between will be on the 1st blendshape you made you need to type '1',
if its blendshape later down the list, count how many over it is and type its corresponding placement number. (you could always re-name your
blendshape objects before you add them as eg. '1_R_TopEyelid', '2_R_BotEyelid' etc.
if you now slide you blendshape, you'll notice the inbetween has been placed at the value you selected (0.5)."
Hope peeps find some of the stuff I post useful...