UIFIS/OUP/MainWindow.xaml

<Window x:Class="OUP.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:OUP"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="50"></RowDefinition>
            <RowDefinition></RowDefinition>

        </Grid.RowDefinitions>
        <DataGrid IsReadOnly="True" ItemsSource="{Binding CashRegister}" Grid.Row="1" SelectedItem="{Binding SelectedCashRegister}"  AutoGenerateColumns="False" >
            <DataGrid.Columns>
                <DataGridTextColumn Header="Продукт" Binding="{Binding Product.Name}"></DataGridTextColumn>
                <DataGridTextColumn Header="Цена" Binding="{Binding SupplyProduct.CostDeliveredProduct}"></DataGridTextColumn>
                <DataGridTextColumn Header="Дата"  Binding="{Binding Dates.Date}"></DataGridTextColumn>
            </DataGrid.Columns>
            <DataGrid.RowDetailsTemplate >
                <DataTemplate>
                    <DataGrid IsReadOnly="True" ItemsSource="{Binding CashRegister }" AutoGenerateColumns="False">
                        <DataGrid.Columns>
                            <DataGridTextColumn Header="Наименование" Binding="{Binding Product.Name}"></DataGridTextColumn>
                            <DataGridTextColumn Header="Стоимость" Binding="{Binding SupplyProduct.CostDeliveredProduct}"></DataGridTextColumn>
                            <DataGridTextColumn Header="Дата" Binding="{Binding Dates.Date}"></DataGridTextColumn>
                        </DataGrid.Columns>
                    </DataGrid>
                </DataTemplate>
            </DataGrid.RowDetailsTemplate>
        </DataGrid>
        <StackPanel Orientation="Horizontal">
            <!--<ComboBox Height="30" Width="150" Margin="100,10" ItemsSource = "{Binding Product.Name}" DisplayMemberPath="NameStatusOrder" SelectedItem="{Binding SelectedStatus}"></ComboBox>-->
            <!--<Button Width="150" Height="30" Content="Добавить"  Command="{Binding Update}" Margin="20,10" Click="Button_Click" />-->
            <Button Height="30" Width="178"  Content="Обновить" Command="{Binding UpdateOpenWindow}" CommandParameter="{Binding CashRegister}"/>
            <Button Width="150" Height="30" Content="Добавить" Margin="20,10" Click="Button_Click"/>
        </StackPanel>


    
    </Grid>
</Window>