Had a first in our home game yesterday and wondered if people could help us out with a ruling.

7 players, no limit hold em, blinds £1 £2.
Under the gun Player 3 calls BB of £2, players 4 and 5 fold, player 6 calls £2.
Player 7 on the button raises £4 to £6 total.
Small Blind folds. Big Blind re-raises all in with his remaining £5 to £7 total.
Player 3 calls extra £5.

Now this is where the discussion began....

Player 7, out of turn, declares "all in", which would be an extra £30, forgetting that player 6 was still in the hand. Player 5 then said that ignoring the out of place bet, if player 6 was not in the hand player 7 could only call not re-raise. The rational being that player 7 could not raise beyond player 2's all in if player 3 only calls that all in. However, should player 6 wish to raise that's ok as he's responding to player 7's original raise of £4 more.

This argument went back and forth for some time as some of us thought that you can always re-raise an all in raise if there are more players in the pot than just the all in player and you. Others thought it gives a potential advantage in certain situations eg, you can raise to nearly put someone all in knowing that if they go all in and someone else calls you have the opportunity to re-raise.

My view was that it's always a bad idea to simply call an all in with other people in the pot, raise or fold! Regardless of the debate on the quality of the call, does anyone know what the official rules are, or where I might be able to find them? Have looked quite extensively online but can only find hand rules and casino rules which don't go into the intricacies of these sorts of scenarios.

Many thanks!

CD