Answer
IFS's out-of-the-box EDI handling for this area is built around the EDIFACT message format rather than X12 natively, so receiving an X12-format acknowledgment requires either converting the incoming X12 message into IFS's equivalent EDIFACT-format message before importing it, commonly done at the integration/translator layer ahead of IFS, or building custom code/transformation logic to parse and handle the X12 format directly within your integration setup — there isn't a native out-of-the-box handler that consumes an X12 856/997 acknowledgment format directly.