Complex sentence: Stan feels that it would endanger he and the rest of his family if it were to be exposed that Roger is an alien and living with them; however, Roger is able to skillfully use disguises to exist on the outside world.
Split into simpler sentences: Stan feels that it would endanger he and the rest of his family if it were to be exposed that Roger is an alien and living with them. However, Roger is able to skillfully use disguises to exist on the outside world.