argonautweakend posted...
"he seems to agree that we should"
uhh yeah? you never gave them permission to take the car. They literally stole it.
For that matter, your brother/SiL would have no legal recourse if your parents just took their car right out of the driveway if they haven't formally transferred ownership. A misinterpreted text isn't going to hold up to any sort of scrutiny when the ownership paperwork is all still with your parents.