Split assembly jobs

We would like to be able to split the whole job with sub assembly's. Currently you can only split jobs that do not have assemblies. We've had a few times now during production, a customer ring up and ask for an urgent delivery of the product, and being half way through the production process it would be beneficial to be able to just split that job as it would already have the correct routing completed or not yet started and prioritize that urgent quantity. We currently would have create a new job from a template, if ones made for the specific job, then go through the original job and find out what been completed and what still to be made then on the new job, close or complete the corresponding jobs and route that new job in for urgent despatch.