Splitting deliveries based on maximum value is not an easy task, because it implies understanding not only pricing, but also certain knowledge of the processes in logistics.
There are a lot of different business cases you need to consider if your client insists on automating the process.
Here are some examples:
Are partial deliveries allowed?
Is complete delivery required?
Do you have configurable materials in the document with pricing on sub-item level?
Does a customer get free articles based on the quantity of delivered articles of another product code?
Are there some logistics discounts/surcharges for pallet/truck optimization?
You would probably wish to deliver everything with a single truck if the total weight/volume/product combination allows that. What sort of internal controls or communication between departments could be used in such cases?
Having this in mind, sometimes it makes more sense to block an order that exceeds a predefined value and allow a knowledgeable person to perform the changes manually after speaking with warehouse/ transportation planners.
Theoretically you could achieve delivery split on maximum value with a custom VOFM routine, but most probably the logic would be quite complex, impact negatively the performance, not easy to extend/maintain, could be challenging to explain the split results to the end users.