My name is shade. Am 18 years, I applied for family reunion visa and my documents have been verified. They listed some documents for my dad to bring but the house he's living is full. Can he use another person house contract instead of his?
You need to prove that you have a place to live once you arrive in Germany.
The easiest way to do this is to show that there is enough room to live with your dad.
If that is not possible, you will need another option of staying. Maybe somebody else (another relative or friend) lets you stay with them long-term. Or you have enough money to just rent another apartment just for you. Or your dad moves to a bigger apartment.
But you need to provide documentation that you have a place to stay long-term.
So yes, you can provide another persons rental agreement, given that that person agrees to you living there long term.