Move inventory to a new SKU

(NAV 2009 R2)

We've got a user request about moving inventory of old SKU, i.e. location based, to a new SKU, due to change of vendor. We could use negative/positive adjustment of old/new SKU to achieve the purpose, but there are a few SKU's and for each pair of old/new SKU, we need to do it for more than 70 locations, which obviously is time consuming. Is there a better way to do it? Thanks.