[otrs] How could the customers change the ticket id?

hi all: I want some of my customers in one class,so they can view the tickets from others. I use the MultiCustomerIDs.For example: Customer A Primary id: cusA Sec id: web -------- Customer B Primary id:cusB Sec id: web The problem is when i use the customer web interface or email to creat a new ticket,i can't select the ticket id.The new ticket id always be the customer primary id cusA.And the Customer B could see it. There are many customers in one class,so it's difficult to set up like below: Customer A Primary id: cusA Sec id: cusB -------- Customer B Primary id:cusB Sec id: cusA How to achieve this requirement