They most likely belong to Lambda Galaxy. FM:Crusader Clans p154 shows their location as being the Deep Periphery, and specifically mentions the 22nd PGC who are mentioned in Explorer Corps p52. Also mentioned in FM:CC are the Falcon Stoop Naval Attack Star and 74th Battle Cluster. These are referred to as the Falcon Stoop Naval Assault Star and the Raptor Battle Cluster in Explorer Corps, but they have the same commanders so are most likely the same units.
The Trinity Solahma Trinary are therefore most likely a part of the Lambda Solahma Cluster.
Hope that helps,
Chris