I figured out how to do it in adobe Lightroom. I add my photos to my LR catalogue by importing them to the catalogue. Go to the map portion of the program - the photos will stay displayed in the filmstrip on the bottom of the screen. In the map search bar at top, type in where the photo was taken then the map comes up in the window. I select the photos I want to mark then drag and drop them where I want them on the map. That populates the gps field with coordinates. I them save the metadata to the files, command S I believe on Mac, and that's it. tks all! UPDATE:
So unfortunately I did not have good luck so far w/ LR. The pics I have to work on are old and have basically no metadata showing except for the date taken, or as Finder shows it, Content Created. I add the photos to the LR catalog and make my location changes. As soon as I save the metadata to file, the Created and Modified dates change to the date of the metadata update in the Mac Finder and Get Info panels. Also, the only way I could get the Date Created field in LR to stick was to apply the date by using a Custom Preset entry. Each time I did the date change either on Add or added it after the addition to the LR catalog, it did not stay.