The steps needed to achieve it are:
- Commit your input projects the to the cloud (REVERSE will be needed)
- Explode all components and polygons (generally everything, you need only basic components. Numbered tags will colide you might want to remove them).
- Start a new project only for panelization with a single PCB document
- Mark the free components from the first project and copy them
- Open the panel PCB and paste the components (make sure your placement is correct moving them is somethimes tricky)
- Repeat for every PCB you need on the panel and for every copy of it
- Export manufacturing files as normal.
- Reverse the changes on the input projects trough reverse option (undo simply does not have a long enough buffer)
Good to know:
Since the part labels are unique in a standart PCB when making the panel every part label that colides with an existing one (all if you copy the same board) will make the new label to have a "_X" in the end as X is the number of the copy (1,2....).
I hope this helps you with panelization in CM.