Anytime you create an Avatar Seat, we recommend that you also include Catcher & Pitcher Nodes as well. The Catcher & Pitcher Nodes indicate the locations two Avatars stand when performing a cooperative animation, like a hug or handshake. The distance between the two Nodes is extremely important and should never change, or else you risk these Animations not working.
The best way to insure that you do not accidentally change this distance between Catcher & Pitcher Nodes, is to Merge the Nodes, along with the Seat Node and Placeholder Avatar Model, into your model from a preexisting IMVU provided Max file.
You can easily merge these Nodes from the Example 3D Room file found in the IMVU Unified Installer.