Am not sure how to answer this one. I assume that your rail portion would cost you more than £7.00 if you didn’t buy the Derbyshire Wayfarer ticket or you are travelling by bus before ENCTS cards are valid?
Bus companies are usually reimbursed for ENCTS travel as the price of an adult single fare less what is called a generation factor, as companies should be no better or no worse off if there wasn’t a scheme. In my area, this equates to companies being paid approximately 55p in the £ of the revenue foregone.
With area tickets such as Wayfarer, I have come across schemes where the operator of the bus on which you purchase your ticket retains all the revenue eg Bws Gwynedd once upon a time. However, if rail travel is permitted it is more likely that each operator in the scheme receives a percentage from each ticket sold.
Without knowing the price of the single bus fares for your journeys or cost of rail fare, given the low price of the Wayfarer ticket, I suspect the bus company would be better off if you presented your ENCTS card.