In the past I used Companion link to sync my Palm with 2 PCs. I found it worked for me the important thing was to make sure that PC1 and device were synced then to sync with PC2 before making any changes there. Before you leave PC2 sync with device and then sync with PC1 before making any changes.

This worked for me using the Palm but I knew that I was in control of all the changes to my data.