When a client wants to pay the full membership at once, you can select that option in the contract of the client. If you choose the option "pay complete membership," the system will create all invoices till the end of the membership and will merge them into one invoice.
Please note that you are only able to use this function when the contract has just been created. As soon as a second invoice has been created, this function is no longer available. You can then choose to "generate next invoice" for the rest of the membership.
Tags: contract, invoices, customers and staff, pay all