An Advance Payment means contractually due sum that is paid or received in advance for goods or services, while the balance included in the invoice. But in odoo, there is no feature for advance payment from the purchase. This module will provide that feature. You can make register payment from purchase order while creating a purchase order. It will also manage journal items, so you do not need to worry about journal management. You can also use advance payment from another purchase order(*Only if both orders have the same customer).