Thank you for your post!
If the Bento Application was on your Apple Account for iOS you may be able to contact Apple to retrieve the software. New devices and iOS Versions may also not allow it to be installed.
I'm also going to move this thread from the FileMaker Community Feedback Space to the Discussions Space where others might find your post easier and offer further advice.
Thanks so much for the rapid and supportive response.
After I posted I went onto the "purchased but not on this iPad" in the App Store and too my great delight there was Bento and I was able to download and install it on my iPhone 6s and iPad mini2 - and it runs and syncs on both under IOS 10 - amazing