If the quantity of new papers is too great to interfile into the existing arrangement, but can be accommodated at the end of the collection (without forcing major stack shifts for material shelved in Beinecke), append the material as an additional series at the end of the collection and call it “[year] Addition”, or “Additions Since [year],” as appropriate. Record date of acquisition/addition to the collection at the series level. Arrange papers in the “addition” in an order consistent with the arrangement of the rest of the collection. Continue to number the boxes and folders in sequence and update the finding aid and catalog record to reflect changes in the collection. Make certain to start your “addition” with the highest unused folder number. This will not always be the last folder number in the finding aid, due to the occurrence of irregular numbering sequences.