Why is it so limiting to show different parts as the same item number? It is understandably "technically incorrect" in the table, but sometimes two separate parts need to be shown as interchangeable. It is more incorrect to have skipped item numbers after merging cells in the table. Besides, it is for mere simple reference in the drawing view for a balloon to point to a single part.

It IS possible to display the item number count correctly when merging cells by creating the parts configurations to begin with. But that is NOT a viable option for an existing set of parts that are already used across hundreds of assemblies. 

Another option is to have a second sheet or view displaying an alternative configuration, but for simplicity of presentation, abbreviated visuals for assembly are needed, especially when there is no need for fumbling through multiple pages and views, if it can be avoided.

So, why not just offer a button for consecutive numbering when absolutely needed?