You seem to have the idea here a bit wrong.......
The seats have nothing to do with engineering, means nothing to the engineer.... It is the RTA that cares about the seats..... People often get this wrong..... Even if a car is engineered, it still has to meet the NON-NEGOTIABLE STANDARD ROADWORTHY REQUIREMENTS.
Sure the engineer can 'engineer' the bride seats, But RTA can/will still knock it back....
EDIT: Things like seat rails is the engineers business, just not the actual seats themselves