Analytics Software

I'm trying to automate the Import of two files into a single FDM location. The two files cannot be concatenated into a single file. The first file is the file that the user selects. The second file is generated by a mapping (external to FDM's internal mapping process) that occurs when the first file is imported. The second file will be imported to an "alternate" hierarchy in a custom dimension with all other fields being the same as the first file. The second file will be imported into FDM with an "Append" import type in an automated fashion since the users cannot be trusted to append the second file manually or load to an additional location. Is there a command in the API that I can use in the ImportAction script to perform an Append-type Import? If not, is there an alternative way to accomplish this without relying on additional user input? Thanks in advance.