Sometimes we ship orders from our warehouse and at times we dropship orders from a vendor. We have routes setup for each scenario and they work perfectly. The route is for normal delivery from our warehouse is selected by default which creates one delivery for the order.

But we need to CHANGE the delivery to dropship without having to recreate the order. I can change the "Source location" of the order's Delivery from our warehouse to "Partner/Vendor" which changes the label for "Delivery" to "Dropship" on the smart button on the order but it doesn't trigger the dropship route. 

I want a Buy operation to get created once the delivery source location is updated OR when the delivery on the order is duplicated with the Partner/Vendor as the source. Especially the same rules configured in our Dropship route.

Is this possible ?

Once an order comes in, based on the routes created, a delivery is created for that order which is what we want to reserve the inventory.

At this point, how can I get the a dropship route to get triggered? I have made one called Dropship with one buy route:
" When products are needed in Partners/Customers,
a request for quotation is created to fulfill the need.
Note: This rule will be used in combination with the rules
of the reception route(s)"

this gets triggered beautifully IF it is selected when the sales order is made but I want it to also trigger when a new delivery made for an order