online vs offline tickets

i have an event where i have already sold 400 tickets in a category with prefix sp- I now want to sell tickets “on the night”. I have a roll of green tickets with numbers on them. If i change the starting number now, after tickets already sold will that damage tickets already sold, or can I just change that to reflect the starting number of the physical tickets and issue myself 100 tickets to represent the physical tickets on the night.

i hope that’s clear.

I have the pro version that allows me to set prefixes etc.