your wife and kids must enter the UK within 6 months of being issued a family permit !, it doesn't mean they can only come to the uk for 6 months.
Family members who come to the UK with an EEA or Swiss national, but who are not themselves nationals of an EEA country or Switzerland, can apply for a residence card (with some exceptions - see 'Family member residence stamp' below). The residence card confirms their right of residence under European law.
A residence card is normally valid for five years, and takes the form of an endorsement that is placed in the holder's passport.
If you want to apply for a residence card, you must complete application form EEA2. You can download the form from the right side of this page.
For your application to be accepted, you must provide a valid passport and evidence that you are a family member of the EEA national. See section 9 of the EEA2 application form for details of the supporting evidence that you must provide.
http://www.ukba.homeoffice.gov.uk/eu...ereuropeanlaw/
