Cypher Lord Of the Fallen

[wako1302]

quote from dataslate

Cypher can be selected as part of a primary detachment from the following codexes: Codex: Adepta Sororitas, Codex: Blood Angels, Codex: Chaos Space Marines, Codex: Grey Knights, Codex: Imperial Guard, Codex: Inquisition, Codex: Space Marines or Codex: Space Wolves. Cypher does not take up any slots from the detachment’s Force Organisation chart. He may not be included in an army that includes any models from Codex: Dark Angels.

So I can include Cypher in my army without using a slot, but if I choose to take the Cypher Formation (Cypher & 1-3 units of Chosen) would they still be classed as part of my Sisters Arm, would they ignore the Allies rule, would they take up a slot.