What about a Duardin Cults book, leave Kharadron out of it, Fyreslayers hear of the Gazul worshipers and after a couple of contracts commission them to help resurrect Grimnir, with this comes ethereal Dispossed Units that with arm and head swaps can be regular units in a hypothetical Grungni battletome, and/or they encounter Daughters of Valaya and join them in their quest since both FS and DV are seeking their ancestors.
If this happened would it be preferable to a Kharadron/Fyreslayers soup tome?