Is there a way I can dynamically add all domain and guest users to a project?

There are two user groups namely *Domain Users and guest. These are "hidden" user groups representing "all registered users" and all guests/visitors respectively. If you assign certain rights in a project/category to these groups, you never need to update these user groups because they are dynamic. Since these won’t reflect in the "add new user", you will * have to mass-add them.