D:OS companions aren't much deeloped so I wonder if it's more you want try different party builds with new companions because you feel Henchmen don't fit.
If that's the case, there's a mod that should be a game feature: It allows create 4 characters at party creation:http://www.nexusmods.com/divinityoriginalsin/mods/21/?
I play my replay (single player) by using this mod and beside very minor points it's great.
Its documentation (links above) lists suspected problems, for me none are a real problem. For now (party level 6) I only get two occurrences where my 2 main characters wasn't involved in some mutual dialogs but the character 3 had taken a dialog triggered by proximity. To minimize the problem I use the diamond formation and leads with the character I want for talk (luck and charisma focus).
The second point I quoted and not listed by the mod documentation, is the characters 3 and 4 won't be considered as your main characters but not as Henchmen/Companions, and I quoted one side effect: They can talk to NPC with the full dialog options, but don't have the shop button. Ie for buying stuff this will be your two main characters only. Beside that, it's a great mod to make a replay and try an exotic party build finely setup at new game creation.