Contact Pairs in Solid Mechanics

Hello,

I'm implementing a model about a sphere of a linear elastic material being squeezed between two plates (lower plate rigid, upper plate moving downwards).

To consider the deformation of the sphere, I tried to define contact pairs at the upper (respective lower) pole of the sphere. These contact pairs are defined in the Model - Definitions - section of the model tree, but can not be exploited in the boundary conditions section of the Solid Mechanics section.

Is the possibility of a contact pair boundary condition simply not implemented, or is there any additional issue to consider?

Thanks in advance and regards
pwb