Простите, что на английском, просто из первоисточника.
A family member of an EU citizen is a family member of a citizen of any of the states mentioned above, who is a:
1) spouse or a registered partner,
2) parent of an EU citizen under 21, who actually takes care of this young citizen,
3) descendant under 21 or such a descendant of a spouse of an EU citizen and descendant or ancestor or else descendant or ancestor of a spouse of an EU citizen, who is due to meeting his basic needs dependent on nutrition or on other necessary care provided by this EU citizen or his spouse, or was dependent on this nutrition or care immediately prior to entering the territory, in a state of which the person concerned is a citizen or in a state in which the person concerned has permitted stay.
Besides this, as a family member of an EU citizen is understood a foreign national who proves that:
1) he is a relative of an EU citizen that is not specified above if:
а) he lived with this EU citizen in a common household prior to entering the territory in a state of which the person concerned is a citizen or in a state in which the person concerned has permitted stay;
b) he is due to meeting his basic needs dependent on nutrition or on other necessary care provided by this EU citizen, or was dependent on this nutrition or care immediately prior to entering the territory in a state of which the person concerned is a citizen or in a state in which the person concerned has permitted stay; or
c) he cannot take care of himself without a personal care provided by this EU citizen due to serious health problem; or
2) he is in a permanent partner relationship with an EU citizen, which is not a marriage and with whom he lives in a common household; when assessing the durability of the relationship, especially the nature, strength and intensity of the relationship will be taken into consideration.