grammatical number - "... any change, or addition, is ..." vs. "... any change, or addition, are ..."

In the sentence below is has been used, but there is some disagreement in the office over whether it should be are:

This is necessary to ensure that any change, or addition, to existing
features is communicated to all relevant parties and that approvals
are documented.

If the subject is change and it is singular, wouldn't is be correct? Even though features, parties and approvals are plural, they don't matter for the verb agreement as none of them is the subject. And using or with addition doesn't make the subject two things, it is still one. Am I missing something?

Answer

You are correct. The relevant portion is "change ... is", so you use the singular form. You could also say "any changes or additions to existing features are communicated" to use the plural.