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You're being charged the $30 fee because you're bronze.
TBH I wouldn't worry about selecting seats. As a family of 4 on the same booking, I'd be confident the system will pre-allocate you a block of four in the centre of the plane so the seats will be pretty much all the same anyway. They charge an extra fee for 71D these days.
OP said a family of 5. Could make selection interesting?