You can still enter new people onto your envelope list, even after renumbering. To do this, you would add that person or couple to the envelope list in the current year, like you would for any new contributor. When you add them to the list, consider not only their current envelope number, but also make sure you assign them an envelope number that will be appropriate for next year. If you want to fit them into an alphabetical order of envelopes, and you haven't handed out your envelopes for next year yet, you may want to run your renumbering utility again to get their next year number where you want it in sequence.