before the transformation, you should check dupplicated verts/edges, as poly's normals.
I suppose the palm's border polys on the right have their normals headed inward.
Do you use "Custom Polygon Display" ?
It's really usefull to detect kinda these topology problems.
Display "Face normals" and set their length if it's unreadable.
I would then, considering all this :
- clean the geometry a bit maybe. OPTIMIZE with non-manifold poly only activated.
- merge verts (changing the relative distance according to you scene)
- maybe also invert normals (outward) or just call a "conform normals".
- then have another go with the poly >> subD transform.
Hope you got it in there
ps : carefull with "Conform Normals". I think it's just relying on the count of outwardNormals >< inwardNormals. Choice'd made according to the results. I understand "Conform the lowNumberCount's direction to the highNumberCount's one".
So CDPO first to be sure >> Custom Polygon Display (optionbox).
By the way, i don't understand why you're not adding the needed polys manually after a combine, then call for the Poly>>subD.