How the open Purchase Order with mixed line items can be split?

I have a query regarding segregation of open  purchase order which have mixed line item (line items of different company code).

Initially, the company was working  under single company code. But now they have decided to separate some of the business so new company codes has been created for those businesses . Now the problem is the open purchase orders which were initially raised for a single company code has to be split for the new and retained business.

So, if someone could advise on  the parameter which can be used to split those open mixed POs, that would be a great help.

Thank you in advance.