Not at this time. When you add a "One Time Item" to an estimate, Aspire will give you the option to add that item to the catalog or not with a checkbox. If you select the checkbox, that item will be added to the catalog and Aspire then does not technically consider that a one time item, and that item can be substituted. But true one time items that are not added to your catalog are handed differently in the background of Aspire and cannot be substituted at this time. If this is something you would like to be able to do, please for the idea in the AHA idea portal!