Not with a native feature within Shopify, but you could build a tool to automate that process if that's a need. For my own interest, since the metafield would remain on the Draft why do you need to transition it to the Order?
Thanks for replying.
I have other processes that use the metafields from the completed order, and I wanted to avoid changing those processes.
The idea to add the metafields to the draft order instead of directly to the order, has come from the need to reduce the number of calls to shopify's api later on in the process.
Thanks again :)