help me for tennacy agreement letter

I am on tiet 2 general visa. I got married on december in my country now i I am sponsoring my wife to join me in uk.
I am living with brother. He owns the property i am not paying anything except council tax. Because he owns house council tax bill is in his name but direct debit is in my account

Is tenancy agreement letter important for dependant visa? I can make tenancy agreement letter making my brother landlord and myself tenant but there is no rent payment transaction on my bank statements. Will it be a problem?

And also i have more than 600 pound always in my account. Do i need maintenance letter from my sponsor? I can get it if its important

tenancy agreement is not required for your wife's application. For her maintenance you can either provide a letter from your employer or submit original bank statements.