How can we improve WHMCS?

When customer replied to our email without the support center, customer added a CC, but the email address added by customer was not reflected on WHMCS.

We contacted the WHMCS support center about this phenomenon and received the following response.
"CCs are only added when opening the ticket. Subsequent replies would not add any CCs present in the email to the ticket."

We would like to be able to add CC's even in the middle of an email exchange.