Using the powershell command Add-TFSpendingChange from TFS 2015 Power Tools I face the following behavior:
Add-TFSPendingChange c:\source\Folder1\docs -Edit
In a computer with one workspace the command check-out the item that is passed as parameter.
In other computer that has several workspaces, the command does not perform anything, not even with the verbose modificator.
It behaves same if I use the local or the TFS path:
Add-TFSPendingChange $/Folder1/docs -Edit
If I use the command TF.exe it works :
TF.exe checkout c:\source\folder1\docs
After creating new workspaces, you need to re-lunch the powershell. Check the screenshot below, I have mapped a project to two different workspaces, and both work as expected: