Is it Possible to Add more Portrait file to portraits.iff?

I finally finally got the hawk23 mod to work through some troubleshooting, with minimal glitches, so awesome. I'm trying to create my own current 2015-16 Draft Class (the one with Karl-Anthony Towns, Justise Winslow, Chris McCullough, etc). I went to the portraits.iff and the portraits_hi.iff, and it seemed like many pictures had been added, not just overwritten--is that true, possible, and if so, how would I go about adding more slots for portraits under those 2 files?