Can you get your dad to sit with you and review this thread?
As everyone has said, a brake line cannot be safely repaired with tape. You cannot contain this hydraulic fluid under hydraulic pressure, which is exactly what a brake line is, with tape. And even if you could, a leak suggests that the line is in need of replacing…it’s failed and will leak again in another spot.
The good news is that replacing a brake line is not an expensive job. And it’ll give the mechanic a chance to check the other lines as well.
Dad, listen to your young one. Have the line replaced. It’s worth the few bucks it’ll cost.