Portrait - editig and adding

I have a question about editing portrait.iff file.How can i add (not replace!) new .dds files into portrait.iff with assignment specific id.
For example - i want to add Kyrie Irving's .dds portrait into my DEFAULT portrait.iff and assign this file id2122.How can i do that?

you cant, you can only replace and grab IDs from here - viewtopic.php?f=144&t=82411

Ok,but how patchers,who had released portrait patches, were able to add +700 portraits into portrait.iff file?

no idea, ask them