CDL school and loophole?

So I'm currently 19 years old and my dad is in the process of helping me get my CDL, I've been looking at local schools. He's been driving trucks for I'd say a safe number is 15+ years. He told me about a friend who's in his same field who hired someone who obtained his cdl via private lessons with an experience CDL driver. My question is, IS there anyway my dad with experience can somehow substitute CDL driving school? As in I believe he said he can sign off my OTR hours and showing me what the school will show me and mail a letter to the DMV that I've received my schooling, or would he need to do something else on his end ?

Additional Info- My dad owns his own local company with about 5+ trucks, He's consistently held his CDL for 15+ years, We're located in California so Schooling is mandated by law in order to obtain a cdl .He and myself have 0 infractions, tickets, marks on our driving record. Any other questions I'd be happy to answer or clarify would just like some insight before I drop 5 grand on schooling if not Necessary.