Gathering what I have written into one big messy XMAS NOVEL

In the computer programming world, there is a saying "Don't reinvent the wheel." which means if there is a program out there that works good already use it in your program rather than writing your own version (which you would have to test too). Computer geeks are if nothing else sensible about not wasting time and effort. Of course, this saying came from the time when computer programmers actually lived in the USA - nowadays these jobs are farmed out to India where the geeks there are willing to reinvent the wheel.
But the point is the above noted saying is particularly useful in writing the Xmas Novel. I will demonstrate using my stories as examples.
I have a story in which two people are traveling in a car out West. Driving in the plains states is boring to the point of coma inducing. So the the two people can tell stories to each other, such as the woman and the haunted house which I wrote earlier and other such stories can be worked into the body of the main story - it might not get published but such a technique was used in "The World According to Garp" which was a bestseller and the main character was a writer.

So I am now in the process of sorting through my previously written stories and picking ones I like and seeing how they can be woven together. I compare this process with decorating a Xmas tree. You bring out your old ornaments, incorporate some new faddish lights and add some other stuff simply because the old ones don't work anymore.
I figure my new Xmas Novel to be about 20,000 words or so but I have not gotten it all together yet so I am still working on it but since this is a good idea that will help in padding your Xmas novel, I thought that I would pass it on.
Keep writing, Frank