Probably you guys know an answer for this. And probably it's quite obvious for everyone except me. Also, before anyone shouts "use teh searhc!": Well, I searched but could find nothing related to my problem. I also asked a few people but I only recieved useless replies or none at all. And yes, I also checked http://cs.elderscrolls.com/constwiki/index.php/Oblivion_Mods_FAQ. But now to my problem:

Let's say I have "Mymod.esp" and "DatArmor.esp".
Now I've activated both .esp's in TESCS inside the "Data" window, and "MyMod.esp" is activ. "DatArmor" appears inside the list of armors and I putt it on "MyMod NPC". It seem to work fine inside TESCS. I see my NPC with the armor. However, when I fire up the game to test it, which also has both mods activated, the "MyModNPC" has not "DatArmor". How can I fix that?

'Till now I either A) used TES4Gecko to merge the esp, which was a horrible idea since it created a lot of "DatArmorDUPLICATE"s, and now I'm doing B) creating a copy of that armor in my mod which I name something like "MyModxDatArmor"
However, what if I want for example to have another race to appear in my mod? Or what if I want to use a faction of another mod? Then I guess neither A) nor B) would work.

Thank you guys.

http://cs.elderscrolls.com/constwiki/index.php/De-Isolation_Tutorial

And at which part of that should I look at?

The idea is that you convert the armor esp to a master file (still being an esp) and use it as master file for your own mod.

So say I change an .esp with diffrent races to an master file, then I would be able to use it in my mod? Would that cause any problem to the race .esp?

It's only necessary for creating your mod in the CS. As soon as you've done that you can replace the master file with the original esp again.