I use control-i to insert a file into another one. With insert, you can navigate to the file to be inserted, using a method similar to Windows Explorer. If you want to choose what part of a file to insert, you can open a new document, which becomes document 2, then insert file two into that document, then choose what part you want, do a control-c to copy that section into the clipboard, navigate to document 1 with control-tab, go to the place where the new material should go, then paste with control-v. This is quite different from your description, but it's the method I have used for almost a decade.
I hope it helps in some way. Others will probably have more to say about this. SR is so flexible that there is usually more than one way to do something.
Mary
