You could use the “No Merge” option in the Pull tool options panel every single time. or You could set the default Pull behavior to “No Merge” in SpaceClaim Options > Advanced. A good best practice is to have every body inside its own component. When pulling on solids separated by components, they will not automatically combine with each other. When pulling on solids inside the same component, they will merge when pulled into each other because the software thinks you are trying to make a single part. For more info on assemblies, here is a link to the SpaceClaim Assembly tutorial videos: http://www.spaceclaim.com/en/Support/Tutorials/Modules/SpaceClaim_Assemblies_Tutorials.aspx