When I last served, a good many years ago, now, my direct subordinates were a mix of military officers (LCol and Maj) and civilians (same level). My direct boss was a civilian, his direct boss was military and that august gentleman had another military officer -the top dog - above him. My little orderly room admin team was, likewise a mix of civilian and military - a civilian was in charge but my personal clerk (secretary) was a military NCO. (One, in the late '80s/early '90s, was a wonderful gal named Murphy: smart, hard working and funny - she regularly deflated me when I needed it. The others, a few names, here or there, escape me, were all good people, too. One was a bit thick, but very attractive, but we (one of my very senior NCOs, actually) traded her away to a more gullible senior officer so all was well in the end.)
Edit to add: My PERs were written and signed by my civilian boss and I wrote and signed both military and civilian PERs. My civilian subordinates wrote and signed PERs for officers and NCOs. One advantage: most of my civilians were ex-military; only a couple were career civil servants.