ROM update using OTA

I have a phone which I installed different apps, I backed up this and created a .zip file which I flash with TWRP. I flash this .zp into 50 more devices, but if I modify one thing on base phone I have to reflash again the other 50 phones, so I need a way to update via OTA. [login to view URL] this seems to do the work, I just need you help me to configure everything correctly. I will provide you with the .zip ROM