Need "free" orders to still process using Purchase Order plugin

-- HikaShop version -- : 3.2.2
-- Joomla version -- : 3.8.5
-- PHP version -- : 5.6.32
-- Browser(s) name and version -- : Chrome

On our store, everything is processed using the purchase order plugin. (Used for in-house swag purchases within the corporation.)

We have a few products that are "free" in that they have a $0 value for the buyer, but we still need to collect their PO info so they can be processed properly. However, if they have only ordered the free items, the store doesn't force them to enter a PO with the payment plugin.

Can this behavior be overridden?

Thank you!

Hi,

In the core of HikaShop, HikaShop skips the payment methods when the total amount is 0. So changing that would require some core modifications, which I don't recommend.
If you only use the purchase order plugin, that means that you don't have any payment on your shop.
In that case, why not use instead the "collect on delivery" plugin which is the same as the purchase order plugin but without the PO number field, and create a custom field of the table "order" via the menu Display>Custom fields in order to collect the PO number ?