In the same vein instead of Anakin actually killing children Clone Troopers could enter the council chambers armed with sabers taken from fallen Jedi.
They could kill the children but the archive footage could be doctored so it looks as if Anakin did it.
That way Vader looks more vile in the eyes of Obi-Wan and the story that comes from Padme's lips seems as more evidence to Anakin that the Jedi are the problem not the new Emperor.