Adam, this is a similar request to 'Starting Point' but relates to the other end - adding more to your workout by selecting another workout & it flows with the 2nd workout template tacked on to the 1st (and ultimately generates one .peridal & one .fit file). I know nothing stops you from continuing to pedal indefinitely and the data is recorded but there is nothing like chasing those targets & intervals.
An example may be a Sufferfest video - SF now have 2 'Extra Shot' videos that you tack on to the end of a full SF workout.
AA