I've just added a SFI on one type to an existing SFI on another, I think it's the same process? Bar the sectors etc for TRI.
In theory it's a 3 hour observed session on an actual type rating course on new type-not dummy trainees as per the TRI course-which means it's almost impossible! The 3 hours is the AOC and has to be done by a TRE/SFE of more than 3 years. Otherwise it's a TRI course on type, minus days 1&2 or the teaching and lesrning(formally core course) part.
I managed to go the 3 hours as I work for the ATO and they have approval to do it. I called around to try and get someone to do my TRI on the type I fly on the same 3 hour setup and no one would touch me
Don't look here often, PM if needed, did this 2 weeks ago.