My friend owns a house with her half brother and he has been renting the house out to some people in receiving the money is for it and as far as we kn

It sounds like the two siblings need to agree to something: either to split the rent as received or for the other sibling's rent receipts to be deducted from their share when the property is finally sold. Best to get an attorney and put it in writing. Otherwise, one should buy out the other.