how to force SrfGrid to work with Trimmed surfaces?, AND to force intersurface, Polylines to connect correctly! correponding points?

Hello GH3D Community,

I've created surfaces over 2 keyframes of an animated character: the Joker. On each surface the arms and legs are in slightly different positions since the Joker's moving.
Once imported to Rhino and "set" in Grasshopper, i trim both surfaces from their rectangular bases so that when sDivide is used it creates and distributes the same number of points on each surface.

But heres the problems:
a) if i use the "trimmed" surfaces with SrfGrid it errors warning: "A point in the grid is null. fitting operation aborted".

I'd learned this was caused by "nulls" replacing position Data Items when the rectangular grid(surface base) was trimmed away. So i used Clean Tree which worked removing all nulls, then Shift Paths\Flip Matrix to create line-endpoint pairs for Polyline\Evaluate Curve.
I Flattened the last Flip Matrix placing all data items in one source for SrfGrid, like in the working Untrim\CopyTrim definition.
This time,.

b) SrfGrid errored with: "The UCount value is not valid for this amount of points",.

So, i substituted a 356 value, numeric Slider in the Addition B param., and tested its range until a valid UCount was found. Then SrfGrid fitted a surface thru the points, BUT,

d) those SrfGrid surfaces are extremely deformed even thought the points preceding it from Evaluate Curve are accurate,
SEE: def: "3b-RGH_SurfaceBlend.gh",

AND,.
a2) if i use Untrim with CopyTrim then SrfGrid works, but since the Jokers limbs WILL be in different surface positions then the blends between the Arm (for example) will rise from its relative FLAT position on the untrimmed Source surface to the Arm on the Target surface, rather than morphing from the Corresponding Arm position on the Source surface,. ..see def.: "4-RGH_SurfaceBlend.gh"

So please let me know,..
1) how to produce accurate surfaces from SrfGrid in def.: "3b-RGH_SurfaceBlend.gh",. ..(NOTE: BOTH these def's contain 2 indentical, "internalized" surfaces, but if def. 3b can be made to work it will also work with Dis-similar surfaces)
2) which component to use or how else to determine the correct UCount value for a specified amount of points(ie:155), re: SrfGrid error: "The UCount value is not valid for this amount of points",.
3) how else to force SrfGrid to work with Trimmed surfaces?, AND,..
4) how to force intersurface, point-blend correspondence lines: Polylines(PLine) to be connected between correctly! correponding positions (Limbs) on the surfaces?,