This .NET method wraps the ObjectARX method AcDbEntity::getGripPointsAtSubentPath.

Public Function GetGripPointsAtSubentityPath(
    subPath As FullSubentityPath, 
    grips As GripDataCollection, 
    curViewUnitSize As double, 
    gripSize As Integer, 
    curViewDir As Vector3d, 
    bitFlags As GetGripPointsFlags
) As bool

public bool GetGripPointsAtSubentityPath(
    FullSubentityPath subPath, 
    GripDataCollection grips, 
    double curViewUnitSize, 
    int gripSize, 
    Vector3d curViewDir, 
    GetGripPointsFlags bitFlags
);