You can only fly an IFR Flight in EASA airspace provided you are a holder of instrument rating. If you decided to convert your multi-pilot type rating, the respective instrument rating will be transferred along with the type rating.
However to transfer the single-pilot instrument rating into EASA, you need to attend either specific competency-based Instrument Rating or the Basic Instrument Rating.
ProfiPilot Training is delighted to guide you thru the ICAO to EASA instrument rating conversion.