Will a 144 hour transit visa be enough

I’m travelling to shanghai from London and will be there less than the 144 hours so I’m planning on getting the transit entry permit. However my flight back (Aeroflot) lands in Moscow before catching a connecting flight to London. Will the flight landing in Moscow be enough to let me have a 144 hour free transit? Also would I need to buy and prove to Chinese authorities a Russian visa? Or if I’ll only be in transit in Moscow before getting the London flight, will this be enough to satisfy Chinese immigration rules on the free transit?