Invoice split

Dear All,

My requirement is as follows:

A particular sales order is created with 100 line items. 50 line items are taxable and remaining 50 line items are non-taxable.

I am differentiating this based on material pricing group. If material Pricing group is A then taxes are applicable and if Material Pricing group is B then tax is nt applicable.(I cannot change this logic of using material pricing group for tax applicability since there are several other parameters why I am using this)

Now my requirement is when invoice is created after delivery, the invoice should be split. Document type ZVF2 should be picked for creation of invoice for taxable materials and Invoice type ZVIN should be picked for creation of Tax free materials. Another criterion is that, these tax free materials benefit can be availed by a particular customer only if they have a TIN number. If they dont have TIN number then these tax free materials will be charged as taxable and there will be only one single invoice.

Please suggest me on this. Hope my requirement is clear.