Hi Omke Oudeman, thx for your help and spending your time in helping the community!
Your tip works perfectly and as I tested it is also useful to share collections between different users and/or different Macs.
Hint for the Adobe Bridge developer team:
Adobe products like Photoshop and Bridge are promoted as professionel software tools. Working in workgroups is pretty normal for professionals. So why not make it simple to share collections between different users and machines? Omkes tip is very helpful but let me remember old times of working with the command line what was and is not very comfortable.