Bulk multi-line find and replacement with Dired instead of SED

Scenario: I have a directory full of code files (in this case, 51 of them) that each need a find-and-replace executed; however, it is adding a line to part of the code, so replace one line with several. This means that SED cannot do the trick; you’ll get errors like,

> > > sed: -e expression #1, char 49: unterminated `s' command

Rather than spending the time figuring out how to encode things for SED, the simplest solution was just to use emacs inimitable dired. It went like this:

1. Open dired into the directory with your files C-x C-d or M-x dired
2. Select all files t
3. Q or M-x dired-do-query-replace-regexp
4. Your query
5. It will ask you to okay the change; you can prevent it from asking this for the rest of the fixes in ALL files with Y
6. Now you have a bunch of altered buffers open. You can save them all with C-x s

It would have been trickier if they were in subdirectories, but with them all horizontal it worked quickly and without issue.