PO creation directly with custom numbering

Summary:

We have a business requirement for PO numbering to follow the SO numbering sequence, so we are thinking to update PO number using API. Instead of going with this approach, just checking - if we can create POs directly with custom numbering? The problem with approach of renumbering PO with API is - for Dropship orders, the link is broken between SO and PO and the new PO# is not getting updated at SO fulfillment level. Also I dont find any ess job that has to be run to update the new PO# on SO fulfillment level. Any inputs please?