Problem with ClumpTemplate()

Hi, I´m a fairly new user to YADE and the programming in general, so I have come uppon a problem with the function ClumpTemplate which I´m not capable to solve.
The thing is as follows:
- I create a SphereCloud with a relative variation of the mean radius
-then I proceed to replace some of this spheres with clump templates, which are obviously way bigger than the spheres itself, resulting in overlapping clumps if the cloud is too dense
-this overlapping results in an infinite force between the clumps and they fly away

Is there a way to avoid this problem, ignoring the initial overlapping of the newly created clumps?

Thanks in advance!