suggestions on easy way to add location data to jpegs that will be recognized in iPhone
After saving image to Photos, open the photos app and double click on your image. This opens your image in a new window. You get a window like the one shown below.

On the top right of the image is a group of icons. Select the first one.  See below.

When you select the first icon - a circle with the letter i in it you get a new pop up as shown below.

As you can see at the bottom of this pop up is an area to assign a location.  While this may seem tedious, once you go thru it you'll see how simple it is.