When Pfc. Armando Soriano was killed in Iraq, his mother benefited from a loophole on immigration law that allows soldiers’ family members to apply for legal residency. But the rules work on a case-by-case basis, and his father, who has been in the U.S. illegally since 1999, faces deportation because he once snuck back into the country. One of Soriano’s sisters is also not a citizen. Such cases are increasingly common as more foreign-born fighters join the military en route to citizenship.