If you look here you’ll see under Haftungserklärung that you need between other things, paychecks from the person who is financing you and their monthly spendings. I’ve also heard from a lot of people that these are generally not really that well accepted unless the person has a very high income. Basically you have to prove that this person has enough money to finance not only their life but also you.
If you have the money it’s much better to just get it on a bank account and show them the Konzoauszug and you dad’s paychecks as proof of where it’s from and you’re done.
Also definitely do not borrow the money from someone as that is against the rules (but 90% of the time they don’t care) wink wink