Why is include file associated configuration section being merged back into web.config when using IIS7 to manage sections?

Question

My web.config file defines a configSource attribute for connectionStrings and appSettings. The two external files are connections.config and appsettings.config. Whenever I use IIS 7 to edit either of these two sections the external file entries are moved into the web.config file and the external file is blank. What is happeniong here and how do I change this behavior so that the files are not "merged" back into web.config?