将项添加到已定义的Collection

Question

所以我有一个用 ControlPanelItem

定义的控件

ShipmentGridView.xaml

<telerik:RadGridView x:Class="SmartShipping.BaseViews.ShipmentGridView"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-namespace:SmartShipping.MainRegionItems.CollectiveShipmentRegionItems"
         xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
         xmlns:lang="clr-namespace:LanguageResources.Properties;assembly=LanguageResources"
>

<telerik:RadGridView.ControlPanelItems>
    <telerik:ControlPanelItem >
        ...
    </telerik:ControlPanelItem>

</telerik:RadGridView.ControlPanelItems>

我在其他视图中使用它是这样的：

FileImportView.xaml

 <baseViews:ShipmentGridView IsReadOnly="True"   x:Name="FileImportGrid">

现在我想添加一个新的ControlPanelItem，但我还想在那里找到旧的。有没有办法合并这两个收藏家？所以我可以这样：

<baseViews:ShipmentGridView IsReadOnly="True"   x:Name="FileImportGrid"> 
   <baseViews:ShipmentGridView.ControlPanelItems>
    <OldCollection></OldCollection>
    <telerik:ControlPanelItem>
    ...
    </telerik:ControlPanelItem>
   </baseViews:ShipmentGridView.ControlPanelItems>
</baseViews:ShipmentGridView>

还是其他方式？