I need to be able to select a file (.txt), move the file to a different directory; however, if a similar file is in that directory append to it. I use similar because the file names will not have the exact same filename but similar. i.e myfile12 is already in the directory and the file I am moving is myfile123 and its contents need to be added to the existing myfile12.

I've explored file dialog for browsing and saving but am not having any good fortune putting it all together. Any place or pointers to start with are appreciated.