At the moment the "Split package" functionality has a major flaw: different shipping services cannot be assigned to different packaging bins. For example, there could be a bin with oversized items which will be shipped by Parcelforce 48h Large service. There could be a bin with normal items which will be shipped by Parcelforce 48h Express service (which is obviously cheaper than "Large"). There could be a bin with small accessories which will even go by Royal Mail.
Please add the function to assign different shipping services to different packaging bins. Without it, split package function is incomplete and cannot be used for the purposes it is designed to be used for.