The group in its current form has been together for 5 years.  And yes it would have been possible for him to have done some session work outside of the band if that's what you want.  They usually take 2 two week vacations during each year.  E.T. is the founding member.  I'm thinking one of the members has been in one (either Cord or Ember's maybe both) of his bands ever since they were in high school the rest have joined up later.