Depending on what bulbs you have in what Lumens and K , it can't hurt to check out using the fluoros as and added light source.
Gotta be better than just reflected light from an over head light using white paint or mylar.
Reflected light looses a LOT of Lumens.
If nothing else I think it would add to the reflected light from your halide reflected light.
As far as my LEDS that are spotlights that shoot a beam and don't reflect light from the tudes,top,sides etc.
Lesser Lumen LEDS or Fluoros work great for branching at a VERY early time period.
I started seeds for a pepper 6/22 and have branching from the seed leaves up and tons of buds from overhead and side/verticle lights.
Can't hurt to try.It can only add to the lumens your plant needs under the canopy.Even if the bulbs are not that high in lumens.
Cheeper than buying and running another halide if it works for your grow.
Getting through the canopy isn't as productive sometimes as placing light under the canopy that put light under it.
I think under the canopy needs less light than the canopy does since it is,by nature shaded growth.
Worth a try either way.
I do think for the few plants you are growing you might want to try verticle lighting on a few and if they seem ok you might be better off adding a few Fluoros than running another halide.
Gotta play with what you have then decide.
Way back when,in the 70's,a lot of grow boxes were a bunch of growlux bulbs placed vertically around the box.Reflective mylar was the only light a plant got from top side.
And that was when Grow lux was about the only light there was for plants.
Post how things work out for you...