So the flex position. Which can be any position TE-RB and WR must still be split out correctly within the 15? So I'll have to drop an RB before Sunday? and add a TE?
Correct.
Complete Rosters must have active (not including IR players):
QB - 2
RB - 3
WR - 4
TE - 2
K - 2
D/ST - 2
Starters should be:
QB -1
RB - 2
WR - 2
TE - 1
Flex - 1 (one of your other RB/WR/TE)
K - 1
D/ST - 1