I gave my colleague who uses a Windows platform my Mac Office document that has ChemDraw structures in it, but they can't edit any of the structures. Why?
Due to the way that Windows and Mac read files that are placed on the clipboard and then embedded into documents, it is not possible to edit any structures placed inside of MS Office documents that are transferred between platforms.
The only workaround is to supply the cdx files along with the MS Office document if you want the other user to edit structures.
This holds true for document transfer from Mac to Windows as well as Windows to Mac.