Revisted old topic; LotserialNbr in subreport

I find that this needs to be revisted. Using the =Next[SOShipLineSplit.LotSerialNbr] is fine if there is just a few serial numbers, but in our case there may be up to 400 or 500 serial numbers for one line item (pumps). I’ve tried using a variable $LotSerial, and either my variable is not listed correctly or something is going on. All of the serial numbers will be listed in a subreport. The main report has DocType, RefNbr and I’ve tried using LineNbr but still not working as needed. The formula for the $LotSerial is being done in the detailSection1, =Concat($LotSerial, [SOShipLineSplit.LotSerialNbr], ‘,’) and there is another variable LineNbr with a value of =LineNbr+1. I also think that there should be more parameters passing from the main report such as InventoryID. I can attach the main report and subreport if needed. If anyone has solution already in place or steps to accomplish this, it would be much appreciated. I also may have a disparity between the main report and the subreport.