Multi VAT on supplier invoices

Dear Community

We have supplier who have multiple VAT on their invoice, for example ingredients will be 0% VAT but delivery charge or an item will be 20%.

How do we process these invoices via posting proposal as once its created via Prelimiary invoice you cannot amend the VAT amount and the only way we know is going to Manual supplier invoice and processing this.

Is there better way of dealing with kind of invoices.

Thanks

Swati