When there is a WHM and BLM on the same team, the BLMs should handle majority of the CC and if the WHM is CCing as well they need to communicate for DRs.

Frankly, WHM is better grouped with a BRD or SMN so that they can do the Sleeps and Heavies while allowing them to do damage freely and Bind when needed.

SCH seems better suited with a BLM simply due to SCH having minimal CCs and BLM having the most making up the difference. SCH also allows BLMs to free cast because of Adlos (those crit adlos so good!). Good SCHs can make up the damage loss that tends to come from bringing along a BLM.