If you are using Shiptheory packages to book mixed pallet shipments, you can select for Shiptheory to use the package (pallet) weight field to control the quantity of each pallet type in your shipments.
To do so, in your Palletways settings in Shiptheory, click the grey Advanced Settings in the bottom-left of the page and scroll down to the Use Weight as Pallet Quantity setting:
Once enabled, when shipping pallets, the Weight field becomes the pallet quantity field. In the example below, the consignment would be booked consisting of 4 Full Pallets and 2 Half Pallets. The total shipment weight sent to Palletways will be taken either from the total weight of the shipment in Shiptheory or the Aggregate Weight field, if specified.