Show and Hide Objects of type GemetryModel3d in WPF Viewport3d

Question

Hello friend of the forum I am breaking my head trying to show and hide several texts made with a class that uses GeometryModel3D elements, the texts must be shown in a viewport3D when a bool type variable is true and hidden when the variable is false. I have dealt with the following code.

void MostrarPropiedadesDimension(Model3DGroup modelg)
         {
             Brush colorTexto = colortextos;
             GeometryModel3D textLong = null;
             modelg.Children.Remove(textLong); // modelg is a Model3DGroup Element
             model_visual.Content = modelg; // model_visual is a ModelVisual3D Element

             if (chkLong) // bool variable from a checkbox
             {
                 for (int i = 0; i < Shapes3D.Count; i++)
                 {
                     double x = Shapes3D[i].Pt13D.X; // Start point X of line elements
                     double x2 = Shapes3D[i].Pt23D.X; // End point X of line elements
                     double y = Shapes3D[i].Pt13D.Y; // Start point Y of line elements
                     double y2 = Shapes3D[i].Pt23D.Y; // End point Y of line elements
                     double z = Shapes3D[i].Pt13D.Z; // Z coordinate of the points of line elements

                     if (Shapes3D[i].Pt13D.Y.Equals(Shapes3D[i].Pt23D.Y))
                     {
                         // CreateTextLabelModel3D is a static method of the TextCreator static Class
                         textLong = TextCreator.CreateTextLabelModel3D((x2 - x).ToString(), colorTexto,
                             false, .3, new Point3D(x + (x2 - x) / 2 - 0.1, y + 0.25, z), new Vector3D(1, 0, 0), new Vector3D(0, 1, 0));
                     }
                     else if (Shapes3D[i].Pt13D.X.Equals(Shapes3D[i].Pt23D.X))
                     {
                         textLong = TextCreator.CreateTextLabelModel3D((Math.Abs(y2 - y)).ToString(), colorTexto,
                             false, .3, new Point3D(x - 0.25, y + (y2 - y) / 2 - 0.1, z), new Vector3D(1, 0, 0), new Vector3D(0, 1, 0));
                     }
                     modelg.Children.Add(textLong);
                 }
             }
}