How to translate objects with different parent together wpf Canvas and Grid - wpf

Question

I'm trying to do a Rotate/Translate/Scale of objects using a canvas for the actual figure and I use a Grid for "thumbs" container (Thumbs are some small ellipses)
I have some trouble understanding the logic behind this example.
<Window x:Class="RotateMe.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:RotateMe"
mc:Ignorable="d"
Title="MainWindow" Height="300" Width="300">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="50"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Button x:Name="AddRectangle" Width="50" Grid.Row="0" HorizontalAlignment="Left" Click="AddRectangle_Click"/>
<Canvas x:Name="DrawingCanvas" Grid.Row="1" Background="Gray">
<Ellipse x:Name="Thumb3" Fill="Azure" Height="10" Width="10" >
<Ellipse.RenderTransform>
<TranslateTransform X="-50" Y="-50"/>
</Ellipse.RenderTransform>
</Ellipse>
<Ellipse x:Name="Thumb4" Fill="Beige" Height="10" Width="10" >
<Ellipse.RenderTransform>
<TranslateTransform X="50" Y="50"/>
</Ellipse.RenderTransform>
</Ellipse>
</Canvas>
<Grid x:Name="ThumbsParent" Grid.Row="1" RenderTransformOrigin="1,1">
<Ellipse x:Name="Thumb" Fill="Red" Height="10" Width="10" RenderTransformOrigin="1,1">
<Ellipse.RenderTransform>
<TranslateTransform X="-50" Y="-50"/>
</Ellipse.RenderTransform>
</Ellipse>
<Ellipse x:Name="Thumb2" Height="10" Width="10" Fill="Green">
<Ellipse.RenderTransform>
<TranslateTransform X="50" Y="50"/>
</Ellipse.RenderTransform>
</Ellipse>
</Grid>
</Grid>
</Window>
So here I have
A Grid over an Canvas (same size)
Each of them contain a 10/10 ellipse that one is render transform -50/-50 and one is 50/50.
I would have expected the same behavior (overlap of the ellipses on both -50/-50 and 50/50)
Instead it looks like this.
So from what I understand from this.
Grid renders from CenterX/CenterY
Canvas renders from 0/0.
Is there a particular reason this is happening?
Why I am asking this, because I wanted to use a TranslateTransform for all my object and if one moves, all should move, but because one translate from 0/0 and one from CenterX/CenterY the same translate won't work on these elements.