Organ pedal foot substitution

Could someone possibly tell me how to code alternate foot organ pedal substitution as shown in the attached image file attach_a.png?

This image is from Dickinson, Clarence. The Technique and Art of Organ Playing. London: H. W. Gray, 1922, p. 117. (Note this book is available from the IMSLP site.)

(Some editors also use curved lines with arrows as shown in the attached image file attach_b.png. This solution with the curved arrows will also work for my purposes if it’s easier to code.)

I located the following related thread in the mail archive: https://lists.gnu.org/archive/html/lilypond-user/2007-12/msg00386.html. The solution proposed in that thread works for same foot substitution, and I intend to use it. However, that solution does not work to indicate alternate foot substitution.

If there is a solution in the mail archive or snippets that I have overlooked, please feel free to point me to it.

Thanks for any suggestions or solutions.

Joe Srednicki

From:	Joseph N. Srednicki
Subject:	Organ pedal foot substitution
Date:	Wed, 24 Feb 2016 19:45:40 -0500