How sum up 3 sub array into a full array?

Hi all,

I have measured 3 similar antenna with the following results:
1st element = 23.6429dB and phase at -69.39deg
2nd element = 23.2117dB and phase at -94.12deg
3rd element = 22.8134dB and phase at -52.007deg

How do I calculate the gain of these 3 elements if put together with a spacing of 225mm at frequency 8GHz at broadside?

If I change the phase to all the same, the gain will improve? example all the phase now is -69.39deg.

Thanks in advance for the help.