I finally did it.

But I didn't do a great job - just a partial job so that we could use the door. I took out the old handle assembly and didn't fill the gap in the door with wood. So they are close together and wiggle a bit and it's probably not real secure (Shhhh - don't tell anyone.) but at least now we can open the door so the kids can use the side door instead of having to use the front door all the time. We really need to do a better job but, for now, it'll do.