To retrieve grip points you can call
Acad::ErrorStatus AcDbEntity::getGripPoints(AcDbGripDataPtrArray& grips,
const double curViewUnitSize, const int gripSize,
const AcGeVector3d& curViewDir, const int bitflags
) const;
for the dynamic BREF.
Note that you must delete the AcDbGripData objects in the grips array.