Your question, frankly, is a little hard to follow. If you are asking what custody relationship your brother ACTUALLY has, given that he apparently is keeping them both during the week and on weekends, it comes down to total time. If they are in his custody at least 40% of the time, looking back over the past year, then according to the Rivero case, regardless of the title given to his time in the decree, he has joint custody -- which has a lot of implications, for custody and for child support. To answer your last question, there is no specific definition of "visitation" -- rights are usually spelled out in the court order. If they are not, they could also be specified, or modified. See the explanations, and materials, posted at:
If all is not clear, your brother should consult with a family law specialist.