How can I Train our Inside & outside Cat to 'not' to go Pooh outside....but to only Pooh in her 'Litter-box'?

You CAN'T. So stop letting your cats outdoors. They're domestic pets - not wild animals - and it's only a matter of time till she ends up hit by a car, eaten by a coyote, killed by a loose dog, catching a disease from other cats, etc.