Adding a new engine in TeXShop

I would like to add a new engine in TeXShop which is able to perform the xindy command in the following way:

texindy -g meindok.idx

I do not want to call the command every time from the command line, instead the dropdown menu integrated in TeXShop is quite comfortable. Unfortunately, I have no idea where the current engines shown in TeXShop are saved. There must have been a change since 2015 because all the posts which I found say that you have to create an engine in ~/Library/TeXShop/Engines but that path does not exist any more.