The scenario that you describe would be an ideal candidate for Library Management using the Data Management System (DMS)
DMS manages the "Master Library/Sand Box" and the data that the designers see to ensure that there are no conflicts caused by directly editing the Master Library that the Designers reference.
Please have a look at the details on the Mentor Web site : http://www.mentor.com/pcb/expedition/pcb-library-management.
If you require further information please contact your Local account manager or raise an Service Request on Supportnet
There are no plans on using DMS at this time so I am creating a library local to my location. The issue that happened to us was, when we first started creating a library, everytime I made a change to anything in the library the engineers would get red box's around their symbols and want to know why their symbols changed. What I am trying to do is to prevent this problem in the future by creating a local library for me to use and test symbols with, than move the symbols to a usable library once I'm done. My understanding from the begining was that this is the best way to proceed. Build a sandbox library location, than a master location the actual engineers would be getting symbols from.
Sorry for the delay on this response
Another method you might consider is the Search Schemes in the library, create one for your use (say Librarian) and have a number of partitions that are only seen usig this search scheme. Use these to build and test symbols and parts and when happy with them then move them to the production partition. Engineers would use the 'default' search scheme in both DxDesigner and Expedition so would not see the extra partitions. For more information on the use of search schemes refer to the help.
I'll look into that option. it sounds like the better solution than to control two libraries at the same time.
Thanks for the suggestion.