FFF would say that you release a new part number. But, it does not say how you name your part. So, you can essentially use a SemVer technique to indicate the same family of functionality with some sort of indication non-compatibility.

   Part Name: MY SW 2.0
   Predecessor Part Number: 150000-0001
   Part Number: 200000-0001

And you have

   Part Name: MY SW 2.0-IBM
   Predecessor Part Number: 200000-0001
   Part Number: 200001-0001

Say your added features to your IBM branch caused some regression. So now you have a second build that is compatible but required a bug fix. Now you have

   Part Name: MY SW 2.0-IBM
   Predecessor Part Number: 200001-0001
   Part Number: 200001-0002

The biggest thing you should take away is that Enterprise Manufacturing and Inventory systems do not try to stuff all the knowledge about a product history into a single field, as SemVer attempts to.