Little pet project I wanna do for myself:

I want to change Rayya (the housecarl for Lakeview Manor from Hearthfire) from a redguard to a nord.
I copied her npc record to a new esp file in TES5Edit and saved.

Then I tried to open the new esp file in the CK, but the CK crashes. Here is the EditorWarnings.txt file:

MASTERFILE: ===========================================================AssertFile: C:\_Skyrim\Code\TESV\TES Shared\misc\BGSLocalizedString.cppLine: 2871LOCALIZATION: Error opening or reading strings file.MASTERFILE: LOCALIZATION: Zero entries or empty block size read from strings file STRINGS/HearthFires_ENGLISH.STRINGS. Strings will be missing.AssertFile: C:\_Skyrim\Code\TESV\TES Shared\misc\BGSLocalizedString.cppLine: 2883Failed to allocate entry array.AssertFile: c:\_skyrim\code\tesv\bssystem\BSTSmartPointer.hLine: 167Null pointer

As a test, I tried to just open the CK loading just HearthFire.esm and Skyrim.esm and I got the same error.

I did a Google search, and I found this: http://www.uesp.net/wiki/Skyrim:Creation_Kit#Notes

I made the following edits to SkyrimEditor.ini:
added bAllowMultipleMasterLoads=1
added HearthFires.bsa to SResourceArchiveList2

Now the mod loads without crashing the CK, but I get errors about missing scripts....
This is what this above link says about that:

I tried copying the scripts from data\scripts\source\hearthfire to data\scripts\source, and I had to overwrite some files (yes, I made a back-up of the directory first). I still got errors about missing scripts when trying to load the mod.

I restored the source folder to its original state, then I tried changing sScriptSourceFolder to point to the hearthfire subfolder. I still got errors when trying to load the mod.

How do I mod HearthFire.esm?