So there is a native “Ship Date” Column in the Sales Order transaction. The default in NS is to have this column hidden and to use the “Main Line”/”Body” field for “Ship Date”. In our environment, we mostly ship everything at once but do sometimes have multiple ship dates. We exposed the column field on our Sales Order form and populate information into both the mainline date and the column dates. As a practice, we use the next/earliest ship date for the mainline field. This way we can still use the mainline searches and have a ship date showing.  You definitely don’t want to build a custom field, because if you use the native one then when you build a search the “Ship Date” field will populate in the same column for the main line and item sublist.