Hello
You can create the Maintenance Plan with Maintenance Plan Category as "service procurement"
Maintain the Purchase order (Type Frame work Order) and settlement Work order in Maintenance Plan.
Purchase order (Type Frame work Order) used for procuring services with external procurement details.
Additionally you can maintain the service too.
When Plan scheduling happen according to cycle length it will generate the Service Entry sheets.So you need do the service confirmation via ML81n.The cost get settled in the work order which you maintained in Maintenance Plan.
Br
Rakesh