I'm trying to find options for building a legal (or semi-legal, even with outdated) rules army including Witchhunters

, Space Marines

, Adepta Sororitas

& Kroot

models, in friendly games :

+

+

+

= ?
My original attempt was to build a Witchhunter army with Space Marine allies, and a contingent of Kroot mercenaries. But it appears that :
- Sororitas

and Space Marines

can't be fielded together
- Kroot

can't be fielded in an army that includes Sororitas

or Space Marines

.
I was thinking of inventing a house rule that would allow this but impose animosity between the Kroot and the Sororitas or Space Marines if within 6". But I'd like to consider "official" options first.
The army's concept is a mixed force led by an Ordo Sicarius Inquisitor of the radical Xenos Hybris doctrine (
cf. Dark Heresy
RPG, Disciple of the Dark Gods), trying to unite the various species created by the Old Ones to fight the Necrons. The Inquisitor's retinue would be modeled to include Adeptus Mechanicus , Eldar and Krork (ork) count-as an unlikely alliance of "semi-heretics and xenos" against a common foe, the C'tan.
Any suggestions to make it work in game-rules terms? Thanks!
PS. My question relates to regular
WH40K (fragments of this alliance will also serve for Necromunda), not playing Apocalypse, where this would not be an issue.