Having the ability to move sheets from one workbook to another without losing any relations would be a time saver.
The current situation is that I have a workbook with a separate sheet for vendor lookups. Now, it will be used across multiple departments and workbooks and carry its own separate permissions. It only makes sense to break it away and make it its own workbook.
The only way that I can see to do this is to create a new workbook, copy/paste the spreadsheet data and then relink forms and other relations.