My company has to package the client and add-ins to push to machines, as users do not have administrative rights. We can have two versions of the client installed on a machine and users can switch between version without issues. In addition, users can now use one Excel Add-in or Excel Business Views and point to more than one ALM version. However, the remaining add-ins are based on the version of the OTACLIENT.dll registered on the machine.
The add-ins work on multiple versions, but the users have to re-register to switch to a different version of ALM. Due to the size of our installation, we upgrade over a period of months. Allowing the add-ins to function regardless of version registered would be a huge help.