How to cascade or copy header billing schedule to lines

I would like to know how to copy or cascade billing schedule from header to lines. All lines will have the same billing schedule. I tried entering billing schedule on the header level first before entering any lines. When I enter contract lines, billing schedule is not defaulted or copied from header to lines. User guide states that "Each line inherits certain information from the contract header such as effectivity dates, bill to and ship to information, and billing rules and schedules. These can be changed as appropriate to allow the contract to conform to the customer requirements. A contract