We had a couple of drivers who had more than 1 car, when they shouldn't. For instance, "Alex" might have 2 1991 Mazda Miatas, one with a color assigned and one with0ut. If I delete the car with a color, it will break the link to any runs assigned to that car, so Alex's total run count goes down by that many. I understand that.

That's not the bug or issue, however.

If I go back to the old event to reassign those runs to Alex, when I do so, it blows away his Member Number, Dedicated Class, and Dedicated Number. Not sure why. It seems like the Alex from the past overwrites the Alex from the present - but only partially.

@Duke Deleting a car from a member profile does not affect existing events and runs. The car data is stored at member level but also at the participant level and even the run level separately.

Deleting it from the member profile would only affect what you see during a registration add/change.

If you went back to a past event to update the car, make sure you check the Apply to Existing runs.

When you update registration even of past events, it assumes you are updating with the current information you have entered into the form. It sounds like the "past" Alex didn't have a member # assigned, so when you updated the registration, it also updated the Member record.