Hi Is it possible to modify a cdt without having to delete it ??...

if you change a CDT that's being referenced to in other CDT, then you need to change the other CDT as well. Taking your example above, you need to modify all the CDT's and upload a new version. Then do an impact analysis that'd modify them on all the processes (make sure you have an app that holds all the processes - read about impact analysis on Documentation). the impact analysis will change the processes but will issue you with a notice that it's not updated the data store. When you go to the data store, there will be a green ribbon on the top indicating that there is a changed Draft for this data store. Click on the link and you should see the updated data store version. Publish the DS and that should do the job.

if you change a CDT that's being referenced to in other CDT, then you need to change the other CDT as well. Taking your example above, you need to modify all the CDT's and upload a new version. Then do an impact analysis that'd modify them on all the processes (make sure you have an app that holds all the processes - read about impact analysis on Documentation). the impact analysis will change the processes but will issue you with a notice that it's not updated the data store. When you go to the data store, there will be a green ribbon on the top indicating that there is a changed Draft for this data store. Click on the link and you should see the updated data store version. Publish the DS and that should do the job.