The quoted sentence is not right. It should be, for example, one of the following: As was customary in that country, the couple decided to get married only after having received the permission of the entire families of both parties [apparently this means the permission of parents, siblings, grandparents, great-grandparents, aunts, and uncles]. It was customary in that country for the couple to get married only after having received the permission of the entire families of both parties, which the couple complied with.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.