Hi - thanks in advance for your advice:

1) I am an Irish citizen
2) Married to South African wife
3) We both live in the UK (permanently)
3) Wife has EEA Family Permit
4) Wife's 13 yr old son living with parents in SA
5) Wife wants to bring the son to the UK to live with us.
6) Parents & son are already planning a visit to UK in 3 weeks time. (3 x visitors visas)
QUESTION:
Can son stay behind with us, and then apply for EEA Family permit while already in UK? Or do we have to apply in South Africa before Entry??? What's the fastest method of getting this done?

Only reason for issue is trip was already planned, and we have now decided on a permanent stay (kid is missing his mother!).

Thanks,