If you require a shipping rule to split the total shipment weight equally across all the custom packages on your shipment, tick the box found under the package options:
For example, if your shipment is 10kg and has 4 packages, each package will be assigned a weight of 2.5kg.
If the resulting weights cause any rounding errors, Shiptheory will automatically readjust the package weights to ensure the weight of all packages doesn't exceed the total shipment weight.
If you encounter any issues, please feel free to contact our support team. You can call us on 0117 403 4313 (UK) / +1 (629) 666-6726 (US) or reach us online here.