More than two adults feeding bluetits

Good evening 

I have witnessed for the first time in around 10 years of observing nest boxes with camera, more than two adults feeding Bluetit chics.

Definitely at least three if not more.....its a frenzy of activityHatching chick the chics are well fed Thumbsup

is this unusual activity Thinking

Also please pass on a very important message. 

I have wireless camera nest boxes....I didn't realise that the transmitter heats up inside box when switched on ....I only discovered this when cleaning at the end of the summer last year. Only 3 chExpressionlesss out of 12 fledged and I watched them die one by one every day....heartbreaking and I think they were being slowly cooked with the hot weather....Please Please turn wireless transmitters off on hotExpressionlessays ....feel really guilty Expressionless