We got our first Frenchie puppy at 12 weeks and he had been fed Royal Canin. I carried on with it for a week and then started mixing Angell food with it, gradually a bit more each day. He seems to have taken the changeover really well. I think he may have a strong digestive system though as he also steals the other dogs food if I'm not quick enough to lift their bowls and sits in a line when they are having treats, so has had some titbits too. We have been lucky so far as what comes out the other end has stayed solid.