Although the family courts are given more credence to half-siblings in relation to contact. The first thing the courts will look at is whether granting a "contact order" will be in the interest of the 7 year old child. This will be very much dependent on the relationship prior to the access cut-off point and if by granting an order will benefit the child. As one court stated:-
"A sibling relationship can be an independent emotionally supportive factor for children in ways quite distinctive from other relationships, and there are benefits and experiences that a child reaps from a relationship with his or her brother(s) or sister(s) which truly cannot be derived from any other. Those of us who have been fortunate enough to experience a sibling relationship are aware of these basic human truths".
Please visit the following for further details
http://www.legislatio...ga/1989/41/section/4A
Hope this helps....Peace