I recently let my sister borrow my car for a week. She filled it up when she was done, but didn't record any info. It would be nice if there were some way to take this into account when adding my future fill-ups. Some way to make an entry like it was my first fill-up again, but keeping all the old data already collected.

I could just create a fake entry using the mileage i know she drove and my average mpg, but I'd prefer something a little better.

Thanks for any help!