if you are asking whether you can use the defendant's rent from the coop to modify the child support, the answer is yes. the rent that he is receiving is income that he did not have before. and, if he argues that the money is just covering the mortgage, that means that his monthly expenses are substantially lower than before. also, if he shows you one rental agreement and the lawyer shows you a different one, that could be evidence of fraud and dishonesty (unless an innocent mistake).
You should feel free to dispute any information from him.
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