OnDragOver & .Parent property

I have a form containing several groupboxes, each gb containing
several controls.  My application allows the user to drag these
controls form one gb to another.  Occasionally, however, the user
tries to drop the object onto one of the controls held by the gb,
rather than right on the gb itself.  

My event handler for the gb has an Accept := True statement in it, to
enable it to accept the dragged item.  Is there any way I can set this
Accept variable for the gb from within an event handler for a
component held by the gb?  I dried various forms of .Parent, but so
far no success.