Nope there is no way to change thingslike this. We have nothing to do with how different forums interact with each other. We only integrate with specific forums. If you switch forum types there is work you need to do to reassign pics. The only thing you can do is with Photopost 4.8 assign the pictures to the new user feature which in your case would be the old user but with his new vb3 userid. This obviously will take you awhile if you have a big gallery.