Add case number to invoices & statements

We see multiple clients through a schools, and we are listing the school as the client, then assigning each case as a client within that school. This is how our funding for services work. Each client is assigned a case number through the school that we use to attach to our statements. You have the function of applying a case number to each case, but it needs to have one more step of allowing that case number to be attached to the invoices and statements.