external editors

What you need to do is add another editor, and then save this as a new preset. Repeat as needed to add more editors. The presets will now be menu items in the second part of the 'Edit in...' menu, so you can edit an image with any editor you want by selecting that menu. The last used editor will be listed at the top, right below 'Edit in Photoshop'.

You can have more the two external editors configured in the preferences. The first is Photoshop. For the additional editor you can configure several presets for  different editors. But it can be only one active at a time.