Mr Hoffman - unfortunately I was unable to solve the problem - maybe I did not do things correctly.
That said there is a solution I am entering incase people find this thread by searching
Before I tell the "secret" here is the list of stuff that AppleCare had me do which did not solve the problem, but may have been necessary. Reset PRAM. Reset GSM. Reinstalled MacOS
What worked :
#1. Open File sharing and click on the ? in a circle for directions on File sharing - I had done all that and some of that was included in your suggestions.
#2. Remove the check mark from the box to disable File Sharing.
#3. Restart the Mac
#4. Open System Preferences again and re-enable File sharing.
#5. Repeat sets 2, 3 & 4 above on the other computer you wish to file share with.
#6. If may be necessary to change the default login names - my wife's computer started with her User name to get into my computer. I needed to change that to my User name.
Also if the computer than does not appear in the list of locations, you can get there by drilling down from "Network" which will appear in the list of locations in finder. In my case once the connection was made once, my wife's computer' listing in Locations was established.
Thanks for your help last night.