Currently, it is rather complex to split a Blob into two Blobs. We need to cut it once into a Squiggle, then cut the Squiggle into two Squiggles then turn each Squiggle into a Blob. It is tricky handling index numbers as they might wrap in different ways. We have done it and now should bring those steps into Blob as a splitBlob(index1, index2) method. Possibly have it accept two x,y points as well... that would make it easier to slice with a line for instance. Yes.
Also see How i can slice a box2d object?