Hello. I am looking at booking an award multi destination award with the outbound and excursionist flight in business. The excursionist flight booked into business with no additional mileage charges without issues with the inbound flight in economy..
If I book the outbound in economy and the inbound flight in business the excursionist flight booked in business but with mileage charges.

Must the outbound flight need to be booked in the same class as the "middle" excursionist flight?
Thanks