Would it be possible to implement a function so that we can control max. reg. per number. Ex. one person registers with the same number 5 times and a message shows that this number has reached it's max. regs.?
LEBT, there are no any limits. You need to customize the default plugin code to make this work the way you need. Unfortunately, we do not offer custom development, and all we can suggest is to find a developer who can assist you with this modification at Oxwall Market: http://www.oxwall.org/market/specialists