Favoriting photos

[Jtshurtleff]

Good day all,
I am trying to figure out how to favorite photos that are not in my Camera Roll. Is this possible? I have a lot of photos in "Moments" but not very many in camera roll, yet. Most of the pictures on my phone were taken on my last couple iPhones and I want to favorite some so that I can have the album be the background for my Apple Watch. Can anyone point me in the right direction?

Thanks guys and gals

 

[Bigeric23]

So, if you go to the appropriate album and select a picture, you don't have the Heart icon at the bottom?