Gazza,
Every one will be different for sure, but if you can get away feeding 3 teenage boys one fillet, good luck to you!
2 fish to the parents = 4 fish. The missus' parents and your parents, leaves 6 fish, which is 12 fillets before you feed your own tribe. Don't get too specific mate or we'll be doing maths all day. And we haven't even started on elderly neighbours and friends getting the odd feed, grandparents etc.
So let's leave it at that eh? It's legal , some will get one feed, some may live alone and keep em all themselves and get a lot of feeds. No one is breaking the law and the price of meat I will never blame anyone.
Muz
PS I'm over 6'3 and over 115 kilo so 3-4 fillets for me :-)