Changing the checkbox square box from square to rounded with WPF

I have successfully created the rounded corner for the checkbox, right now I have issues connecting the control template with other checkboxes, is there anyway to connect the control template to the checkbox generated from the back end?

the first part is the control template modified to change the square box to rounded box

the second part is the checkbox generated from backend and added to the front end

<Window.Resources>
        <Style x:Key="OptionMarkFocusVisual">
            <Setter Property="Control.Template">
                <Setter.Value>
                    <ControlTemplate>
                        <Rectangle Margin="14,0,0,0" StrokeDashArray="1 2" Stroke="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" SnapsToDevicePixels="true" StrokeThickness="1"/>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
        <SolidColorBrush x:Key="OptionMark.Static.Glyph" Color="#FF212121"/>
        <SolidColorBrush x:Key="OptionMark.MouseOver.Background" Color="#FFF3F9FF"/>
        <SolidColorBrush x:Key="OptionMark.MouseOver.Border" Color="#FF5593FF"/>
        <SolidColorBrush x:Key="OptionMark.MouseOver.Glyph" Color="#FF212121"/>
        <SolidColorBrush x:Key="OptionMark.Pressed.Background" Color="#FFD9ECFF"/>
        <SolidColorBrush x:Key="OptionMark.Pressed.Border" Color="#FF3C77DD"/>
        <SolidColorBrush x:Key="OptionMark.Pressed.Glyph" Color="#FF212121"/>
        <SolidColorBrush x:Key="OptionMark.Disabled.Background" Color="#FFE6E6E6"/>
        <SolidColorBrush x:Key="OptionMark.Disabled.Border" Color="#FFBCBCBC"/>
        <SolidColorBrush x:Key="OptionMark.Disabled.Glyph" Color="#FF707070"/>
        <ControlTemplate x:Key="CheckBoxTemplate1" TargetType="{x:Type CheckBox}">
            <Grid x:Name="templateRoot" Background="Transparent" SnapsToDevicePixels="True">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>
                <Border x:Name="checkBoxBorder" Background="{TemplateBinding Background}" CornerRadius="15" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="1" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
                    <Grid x:Name="markGrid">
                        <Path x:Name="optionMark" Data="F1 M 9.97498,1.22334L 4.6983,9.09834L 4.52164,9.09834L 0,5.19331L 1.27664,3.52165L 4.255,6.08833L 8.33331,1.52588e-005L 9.97498,1.22334 Z " Fill="{StaticResource OptionMark.Static.Glyph}" Margin="1" Opacity="0" Stretch="None"/>
                        <Rectangle x:Name="indeterminateMark" Fill="{StaticResource OptionMark.Static.Glyph}" Margin="2" Opacity="0"/>
                    </Grid>
                </Border>
                <ContentPresenter x:Name="contentPresenter" Grid.Column="1" Focusable="False" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
            </Grid>
            <ControlTemplate.Triggers>
                <Trigger Property="HasContent" Value="true">
                    <Setter Property="FocusVisualStyle" Value="{StaticResource OptionMarkFocusVisual}"/>
                    <Setter Property="Padding" Value="4,-1,0,0"/>
                </Trigger>
                <Trigger Property="IsMouseOver" Value="true">
                    <Setter Property="Background" TargetName="checkBoxBorder" Value="{StaticResource OptionMark.MouseOver.Background}"/>
                    <Setter Property="BorderBrush" TargetName="checkBoxBorder" Value="{StaticResource OptionMark.MouseOver.Border}"/>
                    <Setter Property="Fill" TargetName="optionMark" Value="{StaticResource OptionMark.MouseOver.Glyph}"/>
                    <Setter Property="Fill" TargetName="indeterminateMark" Value="{StaticResource OptionMark.MouseOver.Glyph}"/>
                </Trigger>
                <Trigger Property="IsEnabled" Value="false">
                    <Setter Property="Background" TargetName="checkBoxBorder" Value="{StaticResource OptionMark.Disabled.Background}"/>
                    <Setter Property="BorderBrush" TargetName="checkBoxBorder" Value="{StaticResource OptionMark.Disabled.Border}"/>
                    <Setter Property="Fill" TargetName="optionMark" Value="{StaticResource OptionMark.Disabled.Glyph}"/>
                    <Setter Property="Fill" TargetName="indeterminateMark" Value="{StaticResource OptionMark.Disabled.Glyph}"/>
                </Trigger>
                <Trigger Property="IsPressed" Value="true">
                    <Setter Property="Background" TargetName="checkBoxBorder" Value="{StaticResource OptionMark.Pressed.Background}"/>
                    <Setter Property="BorderBrush" TargetName="checkBoxBorder" Value="{StaticResource OptionMark.Pressed.Border}"/>
                    <Setter Property="Fill" TargetName="optionMark" Value="{StaticResource OptionMark.Pressed.Glyph}"/>
                    <Setter Property="Fill" TargetName="indeterminateMark" Value="{StaticResource OptionMark.Pressed.Glyph}"/>
                </Trigger>
                <Trigger Property="IsChecked" Value="true">
                    <Setter Property="Opacity" TargetName="optionMark" Value="1"/>
                    <Setter Property="Opacity" TargetName="indeterminateMark" Value="0"/>
                </Trigger>
                <Trigger Property="IsChecked" Value="{x:Null}">
                    <Setter Property="Opacity" TargetName="optionMark" Value="0"/>
                    <Setter Property="Opacity" TargetName="indeterminateMark" Value="1"/>
                </Trigger>
            </ControlTemplate.Triggers>
        </ControlTemplate>
    </Window.Resources>

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 private void GenerateCheckbox()
        {
            CheckBox checkBoxTest = new CheckBox();
            checkBoxTest.Content = "Test";
            grid.Children.Add(checkBoxTest);
        }