Since there is no native link between the Assembly Build and Assembly Unbuild, how's this being tracked then? Do we just create a custom list field with the Assembly Build/Unbuild? The goal is to identify which assembly builds are unbuilt and where the assembly unbuilts originated from.

Could you use the serialized items of applicable?

I don’t believe NetSuite provides any link between the Unbuild and Build transactions If you need that link then you would need to make a custom field as you said Also Serialization would be a good option as @Netsuite Tragic said

Unfortunately, the serialized items won't be applicable and will just complicate our process. I guess a custom field will suffice for now. Thank you both!