title: Using multiple aggregate in one command handler
body: <p>Provided that I have 2 aggregate, order and customer, and a OrderPayCommand, in the handler, it will check the order status, and check customer balance. If all succeed, it will send an event OrderPaidEvent, which will be handled by Customer aggregate to update balance.</p>
  
  <p>So, how can I check the condition on 2 aggregates in one command handler? So, am I using it in a wrong way?</p>