End users would never be changing table nor index structures.!
You should research automated Front end routines.
I'm still not clear on why you would be adding a PK to a table in production after release to production.
Normally, you would design the database --tables, relationships and indexes --do thorough testing, release to production.
Front end would be automated to the extent they would check latest front end version with what was on their PC. If same version, continue- no change. If latest version of FE is newer/greater than existing version on PC, an automated routine will copy the latest version to the local PC and make it current.
If you need structural changes to the backend, you have a maintenance time with no users on system, make the change to production backend. If ther eis a corresponding change to FE, you change the latest version and put it on a shared drive. When user starts his/her front end, the automated version compare occurs and if needed, the new FE is copied to their PC.
Do some googling--automate front end updates.