_merge?

[Vas]

I was hoping that there was a method for merging new elements into core files.  So you don't have to replace entire files to change one thing, I hoped like I could use an XML _merge method to overwrite very specific values or add new values to something.  I'm not even sure how I'd go about this, but i wanted to be able to change a few things from the core game or even someone else's mod by merging a new item into the trade markets.

[Darker]

I completelly +1 this. Though I'd make it an <Override> tag:

<thingsDefs>
  <Override>
     <thingDef>
        <defName>Existing_thing_def</defName>
        <!-- properties to override -->
     </thingDef>
   </Override>
   <thingDef>
      <defName>New_thing_def</defName>
      <!-- Custom thing def -->
   </thingDef>
</thingDefs>

[Vas]

I thought I saw one mod with the merge command inside it, I don't remember. I'd have to download all mods all over again and look through each and every single file to find it again.  xD  I had hoped someone might know if it really does exist though.