Proper way to add substitute Items in Item BOM

[Maxim-CADman77]

I have some hardware in my BOM that has a substitute for each other.  

So you can use one of either Item in the list.  

Per the ASME guidelines, those two parts share the same item number in the parts list.  So my question is there any way to tell those two parts they are substitute from each other and they come into the parts list sharing that same item number.  

[Maxim-CADman77]

To my mind the minimal solution would be reproducing that same "paper" (old-school) method - make some note in the "comment" field/property.

But even on this way user would face at least two issues:

1. "Comment" property of Item-component is is usual property (not Item-assembly dependant), right.

2. Help doesn't contain any instructions regarding editing "Comment" value.

I would be glad if I'm mistaking...

[Maxim-CADman77]

The desired (maximal) solution - some interactivity on export step (user should be interviewed regarding each and any item that has substitutes defined).