It was not a 4 man crew on this leg.

For those who have not done augmented ops recently, standard practice is that the RP goes on first break, Landing pilot second, and PM-for-landing third.

Current policy is that if you start in a seat, you finish in that seat. There was a time when, on the CA's leg, the RP(FO) and PM-for-landing(FO) would switch rolls after the breaks (i.e. third-break pilot would simply become RP for landing), but FAR 117 (break requirements) and company policy has eliminated that practice.