You know Interior Lighting Overhaul by Sarge198 and Killergrimm, an amazing mod that almost everybody uses.
But this mod is also known to take up too much space: it includes indeed many plugins. That is why I would like to merge this mod in one single .esp with Mator's Merge plugins tool.
Actually I did try but it is not an easy task. If you are familiar with Merge Plungins, you do know that plugins have to be loaded in a raw to be merged, but ILO contains both .esp and .esm and last but not least two requirements.
I finally succeeded to merge several .esp but there was a navmeshes problem, and I am not able to handle GECK.
So if any member has advices to give me about that, I would truly appreciate.

I haven't merged .esp's for quite some time; but if I can recall a few things of note that might help you.

#1: it always helps to not merge everything into one esp, but into maybe 3 or 4 different merged plugins. It not only helps with compatibility, but it helps if you need to redo a merge plugin or something of that manner.

#2: I never, ever ever merged an .esm file. It usually is too complex/script heavy, and really you dont want to be merging those. Same goes for companion mods and quests.

I hope I was able to help dude!

If one certain mod has different .esp files (more than one), it's pretty safe to merge them into one .esp. I have done this with few mods, like More Perks and New Vegas Uncut.

And yeah, don't merge .esm files.

I take note of the advices. I am going to try to merge mods in a few plugins, excluding .esm.