I'm using a Desantis scorpion for my G19, and I noticed there is 2 holes on the outside of each one of the belt clips. Does anybody make a kydex knife or light carrier that I could mount to one of the clips?  Would this interfere with drawing/re-holstering?  What if was horizontal instead of vertical?  I don't think I'd want my reload mounted there, but it seems like it might be a handy spot for another folding knife or flashlight. Or is it just a stupid idea because it would draw attention to my gun?  Please bear with me as I'm relatively new to carrying a concealed firearm, and trying to learn as much as I can.  Thanks in advance for your input.

arent those holes there so you can access the bolts/screws that hold the clip onto the holster body?

anyways, i would not worry about mounting anything to it...why would you? it would imo, add overall bulk to the entire setup, and, having seperate light/knife holders may help if you have to take your gun off, or one of the other items off

more importantly, how do you usually train/fight with what you DO carry? where are your light and/or knife currently positioned? go w/ what is natural for you and the way you train/fight, not unnecessarily changing up something b/c of coolness/style, etc––ie: only change something if it conformes for you to be a more effective/efficient method of carry

my advice: stick w/ how you are carrying your stuff now, try it out; take a training course; go from there; experiment if you have to, see what works for YOU

good luck

The holes don't  seem to be there for any reason that I can see, and the screw heads are on the other side.  
It looks like some guys carry a 2nd knife and/or light, and I thought that instead of a another separate belt pouch w/ clip to hold one, the other, or both, why not use an existing belt clip?  I was thinking of maybe putting a mount for a surefire or streamlight weapon light there so I'd have a back-up light that would also mount to my gun if I wanted it to.  I have carried my light (currently a surefire e1b) in my left front pocket and a knife (kershaw blur) in my right front pocket for years, but I don't know if that is right for me now that I am also carrying a firearm & spare magazine.  
I just got my carry permit, and am looking into additional training to address my lack of knowledge & experience with CCW issues.  I'd like to think I'm experienced, I've shot IDPA and shoot and handle guns on a regular basis, but I've never been able to legally carry concealed before.  I will probably get back into IDPA again as well get more one on one certified CCW training from someone that has BTDT so I can learn.  This whole thing is a learning experience , and I'm trying to figure out what works for me.
Thanks for the feedback, I appreciate it.

Nope. Those two holes don't line up with the screws...in fact, they are on the wrong side.



Using those two holes, I'll bet you could sew a patch of leather or fabric to camoflage the belt clip, or permanently attach a  cell phone carrier.

NP. i am NOT trying to be an ass...i hope that i am really helping/providing ideas/lessons that has taken me yrs to realize...

in the end though, sure, it would make sense to optimize and maybe use one of the belt clips as a clip for something else; for me, (if i still carried a scorpion-esque) holster, i couldnt really mount anything on the clip that conformed to what i do/did carry
my 2nd/3rd knife (2 folders, one in each side pocket) and a fixed TDI on the opposite side of gun for support hand access to "repel borders" (gun grabs) is how i run that; flahslight is similar to you: support side pocket clip
spare mag: support side; i tend to reload using my supoort hand/side if my strong hand is my primary using hand on gun...

for the most part, the only stuff on my "strong" side is my CCW fiream (nothing to hinder the draw or give away its profile) and a folding knife in the pocket; about everything else is on my support side, but can be accessed by my other side

but keep at it, play around with diff setups and gear; test it all, see what works for you and how you carry and train/fight; IDPA, range, classes, etc are ALL great potential training/testing areas for new setups/.etc ...best to test them there in controled environments than under the stress of combat