Absolutely, you can change role members at any time through the app. You can delete a person from the role by long pressing their icon in the specific role you want to change. Then use the + icon to choose a new person to fulfill the role. We do recommend having several backups for each role. Remember that if you change a guardian or executor, the Will automatically updates and you will have to execute the new version.
Feel free to reach out with questions or feedback: firstname.lastname@example.org