Slips can be moved between projects, whether they are for the same client or not. You can move working slips from one project to another in two ways:
Drag and Drop:
From the All client's > Projects view:
1. Find the project where the slips reside.
2. Select the project then select the slips you wish to move.
3. Click and drag the slips into the projects view and drop them on the new project you want them to be in.
4. The slip will be moved to the new project.
From the project view where the slips reside:
1. Select the slips you wish to move
2. Go to Edit > Link To...
3. Search for the new project
4. Click Link
5. The slip will be moved to the new project.