Main assumptions in batch file:
1)Autosigning apk/zip files has already been set up on your computer ('java testsign something.zip' works in command console).
2)7-zip is installed on your computer and is also in your %PATH% ('7z.exe' works in command console).
How to do:
1)Rename mymerge.txt to mymerge.bat and place on Desktop.
2)Select the two zipfiles you want to merge and drag and drop onto mymerge.bat.
3)When asked which file is the primary zip, choose the main update ROM.
4)Choose whether to copy framework or framework and apps.
5)A signed file named “update.zip” will be created on your desktop
This is a simple script. There is absolutely no error correction in this batch file. Use at your own risk.