Each user is connected to each mini market per site, within each connection you give the user a lower and upper approval limit. If the order that is being placed is below or over this limit, the order will go for approval.
Multi supplier baskets, in the classic ordering experience the approval limit is based on the basket value not per order, therefore if the combined basket value is above the user's upper approval limit. Each related order will need to go for approval, you can see if the order was part of larger basket by viewing the related tab within each order. (The new ordering portal is not impacted by this as the approval is based per order).
Flash forecast approval overrides, if the setting within the flash site report has been activated to override the user's approval limit if the forecast has been exceeded, then the orders placed through the related mini markets will require to go for approval.