(written from a Production point of view)
Mentioned in the writers' second draft script of the Star Trek: Enterprise episode "Breaking the Ice", the Merrium System was a star system. According to the script, it was located near a nebula that Enterprise NX-01 had visited three weeks before the events of the episode. The Merrium System was written out of the episode by the time the final draft of the script was written. Though this star system isn't referred to in canon either, the nebula which the early script cited as being near it is.