Does anyone know if you can have an MOQ or Reorder Multiple with Demand Planning? I know that reorder multiple can be used with the "order items" page but it is greyed out when using demand planning (time phased replenishment)... any ideas

MOQ is a no. My typical workaround is to add a custom field on the item level indicating the MOQ and a dashboard alert for when order lines are below that MOQ. The only way to utilize multiples for Supply Planning/Planning Workbench is by utilizing a Fixed Lot Size, this cannot be utilized in conjunction with Periods of Supply though (If you're using Lot for Lot and need multiples, then Fixed Lot Size is the way to go)

yep, that is what I was thinking too - testing fixed lot size right now