Default value (initial expression) in HL7 Field

Epic had changed some of their logic on their Incoming Radiology Results which now require an Ordering Provider even though it is supposed to account for it within the Epic Interface settings.

I was wondering if we are using a custom schema if there was a way to default a value into OBR:16 if it was not valued without having to modify all the DTL's for these Results.

Is there a way to set this via the schema editor or in the background so we don't have to create/update DTL's or create a custom TCP Operation Class??