Recommendations for adding "MUST" attribute to in-production objectclass?

Greetings, list!

I have a custom schema, which defines an objectclass to which all of my "users" belong. I'd like to add a required ("MUST") attribute to that objectclass, but I'm frightened of destroying my users :-)

Is the following procedure safe?

1. Add the desired attribute as optional ("MAY") to the objectclass in my schema. Restart slapd.

2. Apply an LDIF change to every node with that particular objectclass, setting that new attribute to some acceptable value.

3. Ensure that my "create a new user" tools will set that attribute.

4. Change my schema to require ("MUST") that attribute within that objectclass. Restart slapd.

If not, what is the safe procedure?

Is there a better way of adding a required attribute to an in-production objectclass?

Thanks!