Your family members must register their residence within 4 months of arrival.
To obtain a residence card they will need:
valid Passport or identity card, and copies of it
the registration certificate of the EU citizen whom they are accompanying or joining
for spouses of EU citizens, direct dependants under 21, dependants of the EU citizen and of the spouse: proof of existence of a family tie, and that said family members are dependants
for other family members of EU citizens: a document issued by the relevant authority in the country of origin or country they are coming from certifying that they are dependants or members of the household of the EU citizen, or proof on the existence of serious health grounds which make the care of the family member by the EU citizen absolutely necessary, or proof of the existence of a long-term relationship with the Union citizen