Let’s say I got a scratch on my parent’s car. Do I have to tell it to them if it’s not noticeable or it falls under the category of Gneivas Daas?
The issue here is not genivas daas but the fact that you damaged something of theirs, and you would have to pay for it. However if the scratch is so small that the value of the car didn’t go down, then you don’t have to pay them for it. Since it is not noticeable, and they were not negatively affected by what you did, you would not have to ask them mechila.