Hi...Please note that the procedure If he change the company is that his visa will not be cancelled just sponsorship will be changed only if he get the NOC from present employer (Has to follow formalities). And regarding loan case if he resign, present employer will inform to the bank and the bank will hold his end benefits and u are supposed to provide salary transfer certificate from new company.. Also note the new company should be under the approved list of bank or else bank may force u to provide guarantor.(depends on bank)..Third is regarding the family, dependent visas will not be affected unless his visa is cancelled.