Currently you must set the path to the folder that teststand will load its inital configuration through the options. This means that it is not possible to change this via the cmd line wehn launching sequences. Tehre are several work around for this (none of which are very good).
The 'best' solution to this issue would be to add "/configPath "c:/projects/tests1/" " as an option on the cmd line and allow teststand to use this instead of the path hardcoded int he registry.
https://www.ni.com/docs/en-US/bundle/teststand/page/choosing-an-environment.html