Wpf RichTextBox execute command by sending programmatic key strokes

I need to send keystrokes to a RichTextBox which at the and should execute some commands like ToggleBold or SelectAll etc.

I call the following code in a loop to iterate through SomeEvent and SomeKey pairs.

PresentationSource presentationSource = PresentationSource.FromVisual(RichTextBoxControl);

if (presentationSource == null)
{
    return;
}

if(SomeEvent == KeyDownEvent)
{
    //InputManager.Current.ProcessInput(new KeyEventArgs(Keyboard.PrimaryDevice, presentationSource, 100, SomeKey) { RoutedEvent = PreviewKeyDownEvent });
    InputManager.Current.ProcessInput(new KeyEventArgs(Keyboard.PrimaryDevice, presentationSource, 100, SomeKey) { RoutedEvent = KeyDownEvent });
}
else if (SomeEvent == KeyUpEvent)
{
    //InputManager.Current.ProcessInput(new KeyEventArgs(Keyboard.PrimaryDevice, presentationSource, 100, SomeKey) { RoutedEvent = PreviewKeyUpEvent });
    InputManager.Current.ProcessInput(new KeyEventArgs(Keyboard.PrimaryDevice, presentationSource, 100, SomeKey) { RoutedEvent = KeyUpEvent });
}

For example to activate ToggleBold I call following pairs in a loop:

KeyDownEvent, Keys.Control
KeyDownEvent, Keys.B
KeyUpEvent, Keys.B
KeyUpEvent, Keys.Control

I have tried KeyDownEvent - KeyUpEvent, PreviewKeyDownEvent - PreviewKeyUpEvent, and PreviewKeyDownEvent - KeyDownEvent - PreviewKeyUpEvent - KeyUpEvent, but none of them worked.

The RichTextBox actually catches the events but it does not react to them. This is also the case if I send alphanumeric characters (They are not printed on RichTextBox). However if I send Keys.Back it actually recognizes and deletes a character from the text.

The solutions like SendKeys and keybd_event are not applicable since the program will be on the background while the keystrokes are sent.

Is there a way to send keystrokes to a control like they really are sent by the user?