To import Parallels Client settings and connections from command line, please execute the following command in command prompt under the user account:
"C:\Program Files\Parallels\Client\APPServerClient.exe" -importsettings C:\SomePath\SomeFile.2xc
Where C:\SomePath\SomeFile.2xc must be replaced with a full path to the actual settings file you'd like to import.
Please note that path to APPServerClient.exe may vary on your system. Please adjust the command accordingly to it if needed.
If you'd like to override credentials stored in the settings file, please refer to https://kb.parallels.com/en/124695