In most cases our IDC goes to the school of PI (we don't happen to
distribute to PIs or departments; some of the schools do that),
without much regard for the co-PI.  However, in many instances
co-equal PIs have split the IDC between their schools, or an
especially significant co-PI has struck a deal for part of the
IDC to go to his/her school.  This has hardly ever been acrimonious;
it has some times been confusing.  We do not have a fixed policy
on this issue and my guess is that developing a policy would be
more trouble than it's worth.

Stuart Ross
California State University, Fullerton