genius.
Beacons yes, intersections no.
It sounds as if Liffy is a Visual Reporting Point (correct me if I'm wrong) and is therefore known to local ATC, but will almost certainly not be known by the people who process your flight plan in Brussels.
Strictly speaking town names should not be used either (I think!) although they are normally accepted. Rather, a bearing and distance from a beacon or airfield should.
I believe you can also use a Lat/Long position and if this happens to be an intersection then so be it.