What is the D6 family-reunification visa and who qualifies?

Short answer: D6 reunites spouse, registered partner, minor children, and dependent parents of an existing Portuguese resident permit holder.

After your D7 or D8 is granted, you can file D6 for immediate family. Required: marriage / birth certificates apostilled, proof of cohabitation, accommodation big enough for the family, and a subsistence multiplier (50% for each adult dependent, 30% per child).