Lion of Caliban wrote:
I don't know too much about the Shadow Wolves and their interactions with humans. But I don't see too much of an issue. The relationship between Space Marines and their Human allies varies between chapters with some respecting them, others thinking them irrelevant and others still simply use them as bait. But from what you've said I expect they are closer to the mutual respect kind or at least using them as tools. Basically Space Marines are under no real obligation to follow orders given to them by outsiders. But they do follow advice. If the way you're viewing it is the Warlord is a high ranking strategist feeding information and helping organise, then absolutely that makes sense. I mean a good example would be Creeds practical leadership over the defence of Cadia put him in charge of Space Marines, which they accepted for pragmatic reasons. I mean why would a Space Marine Captain on the front line not listen to an Imperial Guard officer in the back line with broader up to date tactical information for advice on the overall war effort? Especially if they are pragmatic and tactically minded. Listen to the guy who has the info and use that to make decisions.

Got a bit rambly so short answer: Yes I think It can make sense for certain Chapters to give temporary command to an attached Officer to hold down the fort while they take the fight to the enemy.