Have a look to JAR.OPS 1.175 (h)(i) + (more important) Appendix 2 (b)(5). According to this, yes you need somebody to satisfy as a Ground Operations Post Holder, but this does not have to be an individual person. You may combine this function with another post holder if acceptable to the authority (e.g. FOM + GDOM or QM + GDOM).
Cheers
GW