Active contours: detect merging cells

[Pablo Wakonigg]

I'm using Icy to follow the size, shape and movement of patterns on the surface of a water body. These patterns behave exactly like living cells in that they move, they have variable geometries and they divide. 

My issue is that my shapes (the ones on the water) also merge, whereas cells don't. Active contours (AC) can identify easily when a cell has divided, but not when two cells merge (because they're not supposed to).

So, my question is: is there any way to overcome this issue? On analyzing the attached file, AC will understand that the white shape has divided, but not that it has merged, and it displays it as two shapes squished together. I want AC to know that it has become one "cell" again.

Thanks in advance :)