I'm sure it'll have to be WIIN-FM since those calls are parked on AM station here in Jackson, MS. Would Merlin have to pay and/or seek permission to use those calls?
Could be the same route they'd need to take if they wanted the WYNY calls - they're currently assigned to an AM station in suburban NY, which has not yet signed on. I'm sure they'd rather just buy the calls outright rather than assign an "-FM" to them, and one would think the same case is such for WIIN.
I think that permission and/or compensation is required from the existing stations even if just a '-FM' suffix is requested.
Likely Merlin Media will just buy the calls outright because both stations (Ridgeland, Mississippi and Middletown, New York) are under-utilized.
WIIN was a silent station until just this week (June 22nd) when the station began a simulcast of Country 96.3 WUSJ Meridian, Mississippi.