Subcontracting with discontinued parts

We use discontinuations all the time but now we are fully subcontracting some products and the discontinuation is not being planned for either the old part or the new part. SAP help clearly says that subreq discontinuation is not planned but with several parts at any one time on boms of over 200 parts, we just can't manually manage this.

I don't believe we are the only one with this problem but I am unable to find any solution - please help!

Thanks