Questions Parent Child Sales/Service Orders?

hi All, a long one i'm afraid. Not sure if this is possible and going to put it in the discussion forums as well, i can't think of a way of doing this without development. 

Currently the customer sends their equipment in as a stock item, they receive the stock item in (serial traceable must be recorded) and then send the item(s) for inspection to their service department. (currently use RM order for this)

From the inspection, the equipment can go down 4 or 5 work flows as we’ve currently analysed.

1. Service – standard service of the item, non-stock item cost added to the order/serial item, the service is carried out and the item is dispatched back to the customer
2. Parts Required – additional parts are required for completing the service/calibration of the item, quote to the customer is generated, if the customer accepts the quote, the parts are consumed, the item is calibrated and sent back to the supplier
3. Unit Failure – the item is beyond economical repair – the item is either returned to the customer or written off (proof of consent is received and associated with the serial).
4. Warranty Return – the item is returned under warranty from the customer, this item is sent back to original supplier, replacement or fix unit received from supplier, these is sent back to the customer
5. Sales Return – the customer no longer wants the part, it’s inspected (if gas detector) then returned to stock

They need to then quote to the customer for the work required for the multiple flows for the multiple items receipted . This is where we have the issue.

When the customer sends in the order, they are quoted for Service/Calibrate for all the items being sent (10 sent in, 10 calibrations required). Upon inspection they can go down any of the routes above.

What I was wondering is if anyone can think of a way of bringing the serial traceable stock in from a customer, splitting the order/receipt by the processes above, quoting against the original order for all the work required?

Is there a parent child relationship within field services or service order or sales orders where we can associate several “sub orders” with a parent?

These sub orders would contain the details for the specific work required per serial – additional parts required, their serials, recalibration etc. and costs – this would all feed back to the parent order for quoting purposes?

There will be a customer reference number for the customer PO for the work recorded on the sales order in customer order reference.

Our current proposed solution is very "clunky", we un-allocate the line of the RM sales order, reduce the line qty down, create copy order, on this child order, we set the qty to 1, add the additional parts required and reallocate the serial in question

they have field services and CRM available. the origin of the work is an opportunity where the original quote is being generated. 

Thanks

Matt