When you move to a new numbering scheme, operators will keep searching by the old number for years, since that is what is printed in the binders, written on equipment and stuck in everyone’s memory. If the old number stops working in search, people go back to the paper copy, which defeats the point of digitizing.
The simple fix is to keep the legacy number on each procedure as an alias, so a search for either the old or the new number finds the same document, and to show both numbers on the procedure for a transition period. Once people have had time to get used to the new scheme, the old number can stay in the background for search without cluttering the procedure.