Greetings, Rodcoles.
Welcome to the Apple Support Communities. We can understand why you’d want to resolve the issue with being unable to add different addresses to Focus.
First, Restart your iPhone and make sure your iOS is up-to-date: Update your iPhone, iPad, or iPod touch
Then, try to create the custom Focus again:
“To set a schedule based on certain times, locations, or apps:
- Go to Settings > Focus, then tap the Focus that you want to schedule.
- Under Turn on Automatically, tap Add Schedule or Automation.
- Choose when you want the automation to happen, then follow the onscreen steps.” Use Focus on your iPhone, iPad, or iPod touch
We hope this helps! Thanks for being a part of the community.
Sincerely.