Simulating Pin Connections

I'm working on a lifting rig under very high loads. I'm trying to simulate the pin connections at the links for each part of the frame. As I understand it, SnS does not do linkages just yet so I'm trying to tackle this in a peice by peice fashion. I appear to be getting results that are well higher than what simple hand calculations would suggest. Anybody have any good advise about how to properly load holes to reduce artificial stressed caused by "puckering".