Not sure if you are talking about Session Rules or Driver Commands.
With Session Rules in the Session Editor, there is a default set of rules that appear when a new Session is created from scratch. You add to these rules using the Add button and, provided you save the Session, those additional Rules will appear in the Session Editor when you next reload the Session. There is no way (that I know of) you can have your preferred set of "default" rules preloaded into the Session Editor when you start a brand new Session.
Driver Commands are added using the Driver Command Rule and, provided you select the commands you want and save the Session, then those commands will be present when you next reload the Session. Again there is no way (that I know of) you can have your preferred set of "default" commands preloaded into the Driver Command Rule when you start a brand new Session.
My thoughts.
EDIT: You can set up a saved "dummy session" with all the Rules and Commands you need and then save that "dummy session" as a new Session with a different name as the Session you need. The disadvantage here is that you cannot do this when the "dummy session" is attached to a different route without fiddling with kuids and config.txt files (always dangerous).