Is there a way when doing an assembly build of a serialized assembly that contains other serialized items to ensure traceability of exactly what serial number of the assembly contains the serial number of the components? E.g. when building qty of 2 assemblies w serial number 10 and 11 and they contain components w number 20 and 21 respectively Netsuite only tells us that serial number 21 was used in the build of number 10 and 11 but not exactly which one

You have to build one at a time or maintain separate record keeping either through a custom record in NetSuite or outside the system.

I just ran into this. Unfortunately NetSuite does not have that granularity when creating work orders with multiple serialized finished goods and serialized component quantities. It will only provide a one to many relationship instead of a one to one. We had to keep track of the serialized components and serialized assembly finished goods separately on a spreadsheet and then created a custom record in NetSuite to hold the values for reporting.

Worth having a look at the lot and serial trace app... it can drill down multi level for traceability

The tracebaility app does not solve for the above. If you record a build that has 10 builds and all the components on one transaction then there's no delineation between where the components went in the finished or semifinished good.

Thanks for the help, disappointing that its not supported. If we create a custom record and upload the serial numbers, would this be recognized in the SN traceability search?

Honestly, it would be best to create your own saved search with filters at that point. Far far less effort for the same return.