Yes, you can use your ATS to collect candidates from various sites into a pipeline, and an annotation of "manual add" within the ATS is a good record keeping practice. The individuals you add are not Internet Applicants, though, until you actually consider them for a particular vacant position and they express an interest in the opportunity. If the manual add flag is a signal to you that you still need to get the candidate to express interest (to apply to the vacancy for which you thought they were qualified), that would be a good idea. Whether you are recruiting or data-mining inside your own ATS, or tracking these passive candidates you discover outside the ATS, doesn't matter so long as you comply with OFCCP's record keeping requirements. If you put them in to your pipeline pool, a position becomes available, you ping them to see if they are interested, and they do not apply to your hiring requisition, they are not Internet Applicants. There are a number of very good slide presentations from past annual conferences about the pros and cons and best practices when using pipeline requisitions. I encourage you to look at some of them.