Custom Message to Customer within Order Page

-- HikaShop version -- : HikaShop Business 2.6.3 [1605112330]

Is it possible to be able to send a custom message to a customer when changing the order status within the order page as you can on the list of orders page

Hello,
There is no option to do that so the solution can be to manually notify your customer or to directly edit the "Order status notification" email via "Hikashop->System->Emails".