Allow non stock (financial) credit note / invoice on obsolete items in sales order (purchase order)

Would it be possible to enter new non stock order (negative or positive) of obsolete items(STKT=O) ?

A possible workaround is to change the stocking type from O to U the necessary time to enter the order but it's a risky solution and I should prefer a "standard" solution.

We 're been receiving complaint from our customer one or two years after the item end using and it's impossible to enter any order, especially non stock orders.

Could we imagine any workaround like a new processing option in P4210 or a new field in the line type definition or a new value in the IVI field in the line type definition (after D, N, Y possible values, a new 'C' value to allow financial document for 'O'bsolete items ?