Photos currently allows you to ASSIGN a location, but I don't see a way to COPY a location from one photo to another, which is what the user asked and what I currently need. So this should not be marked as Solved.
That is the problem with old discussions. The solved mark is two years old, from the very first version of Photos on Yosemite. In with OS X Yosemite we could not even assign a location to photos. We had to assign GPS tags in an external editor, if the camera did not assign the GPS: One year later, with Photos on El Capitan came the ability to assign locations to photos by typing in GPS coordinates into the Info panel or a places name. That was when I wrote this Apple Script, that will read the GPS coordinates from a selected photo and copy them to the clipboard, so we can paste them into the Info panel for other selected photos: Script: Retrieve the GPS Coordinates of the Place of a Photo
Photos on El Capitan allowed Apple scripts to read the GPS coordinates, but the tags were read-only. With macOS Sierra finally came the ability, to modify the GPS tags of a photo using Apple Script. Now I could write the AppleScript that Larry pointed to: Script: Copy GPS tags from one Photo to Other Photos
To use it, collect all photos in an album and drag the photo with the GPS coordinates to the start of the album. Select all photos in the album and run the script. The GPS coordinates of the first photo in the album (in the selection) will be lifted from the photo and stamped on the other photos in the album.
What still is missing - we can modify the latitude and longitude tags, but not the altitude tags of a photo using Apple Script. The altitude tag is documented ans being writable, but trying to modify to gives an error message.