Hi @
redlance,
Thanks for the message!
REST API for the multi-vendor solution is the same as for X-Cart Business and you can create order by using 'POST' method to _path=order/0 end-point.
https://devs.x-cart.com/rest-api/#request-parameters
https://devs.x-cart.com/rest-api/#model-data-and-types
Let me know if it is any help to you.
Tony