Merge Lots without WMS using WIP

Using standard Inventory without WMS, need to merge existing lots from on hand to new lot number. What is best method to use?

Considering using Discrete Mfg but not certain if standard or non-standard WIP is easiest and if work order-less completion is useful. Would need to issue existing lots from Item A to Assy Item A and complete to new lot number and do not want to capture any labor or overhead. Ok with creating BOM but looking for easiest setup and execution.