Chain migration equals chain employment as well. I’ve seen it. I know other FReepers have seen it too. One is employed to work, and next thing you know the whole damned family is on the payroll, and they run the business by either sandbagging, or no show, flu, whatever.
I don’t know how many employers I’ve heard griping about the cussed “_________ Army”, and how to get back control of their businesses.
The same has happened in biomedical research. The study sections that review grants are often a mafia of those who fund each other. It's unfair, and disheartening, at best.
Illegals cannot bring relatives legally. Most legal immigrants can start the chain after they become a citizen. There are probably special rules for refugees, which was an Obama specialty. Today’s bomber was only a few months under 21 when he came (according to a radio report). Over 21 and he would have been Ineligible. Maybe age is flexible in some countries.