Should we allow the demographic balance to be overthrown by the government's immigration policy?

I did a job in Hawaii for a very wonderful couple- she is Japanese and he is from New Zealand. They have the most polite children- their kids actually thanked me for coming to their house! Their home is worth approx. 3 million dollars. They have to move because their work visas are about to expire. They are moving to New Zealand but would love to stay here. They were asking me if our govt. hates Japanese because we do nothing about all the Mexicans that break in and steal stuff. This family would have made great Americans. When I left their house I cried.