Ability to create parent and child expense

[#1]

It would be really useful to be able to multiply bills for single expense. That would give us that opportunity. For example: if you got a project which got same expenses through all project life cycle with same budget - all you need to do it update Actual Amount. But when you bill your customer monthly, once is billed, we're not able to updated Actual Cost for it.

Having this option would make it possible, without needs to add new he same expenses with £0 budget for it..