I am not sure if you just want to add one more property as an infotable, but if it is, follow instructions below.
1. Go to Subsystems.
2. Open UserManagementSubsystem and go to Configuration.
3. If you want to add more seesion shapes, just click "+ADD" button under "User session shape settings". Or you can just add more properties in pre-defined shapes. In this example, I just added a property in "GlobalSessionProperties".
4. Check if you can see this property in your mashup's session properties.
If you cannot see this from your mashups, please restart UserManagementSubsystem after saving it.
Just for informations about adding an Infotable as a session parameter:
Important Note: Infotables as properties should not be used as Session parameters, as they will persist throughout the session and cause performance degradation, especially when the Infotable has multiple rows/ columns