How do my family members actually enter Malta once reunification is approved?

Approval of a family reunification application does not by itself put your relatives in Malta; they still need to enter the country properly. Identita issues an approval-in-principle letter once the application succeeds.

Family members from visa-required countries use that letter to apply for a national long-stay (D) visa at a Maltese embassy or consulate (or another Schengen mission where Malta has none). Relatives from visa-exempt countries can usually travel to Malta and present the approval letter on arrival, then complete the residence formalities locally.