It's an IG army with a Lord Inquisitor ally (and a Vindicare Assassin, but that's besides the point).
I'm asking if I can specifically attach the Priest to the Lord Inquisitor's squad. Normally, the Lord Inquisitor is an Independent Character when alone, but he starts with a retinue of at least three. I want to field a Lord Inquisitor, his two Mystics and a Combat Servitor (and maybe an Acolyte for another power weapon), and an attached Munitorum Priest, but I don't know if ICs can be joined with him, since rules about him are a) from a different codex; and b) from a very old edition....