Southwest Airlines briefly operated the 727-200 during the 1970s. Were these crewed completely by the leasing airline (Braniff ?) or just piloted by SWA pilots converted from the 737 ? If the latter, who or what, occupied the FE station ? This situation seems familiar; I'm sure I've asked the question before.
In the UK, Britannia Airways perhaps faced a similar situation when they had the pair of 707s for a year or two. Third pilot or FE ?