If immigration Office does not approve your application, they must justify their decision in a statement. One reason may be, for instance, suspicion of a so-called "marriage of convenience". If they assume so, the German diplomatic mission abroad (embassy or consulate-general) will then reject the visa for your relatives. You then have two options:
1. Your relatives can object in writing within a month by submitting their objection must to the German embassy- In this letter, you should explain why the rejection is wrong. After receipt of the letter of objection, your family's application will be re-examined. Either your family members will then receive a visa- or their objection will be rejected. In the event of a second rejection, your relatives will receive a so-called “remonstration notice”, which explains in detail why they cannot get a visa. Your relatives can file an action against this decision within four weeks at the administrative court at your place of residence. If that is the case, you should hire a lawyer who can take care of everything.
2. You can file a complaint directly with the administrative court in your place of residence within four weeks. Best is to seek advice from a lawyer.