Beersmith Proper Whirlpool IBU calculations

If I add a Whirlpool/steep hop in beer smith it does not change the IBU of any of my boil hops. Am I correct in saying that it should rise, but not at the level of the boil hops. My thought was to just extend the boil time, but I don't think that would be correct either.

Nope it does not. The reason for this is that the effect has not been modeled very well yet. The only real effect would be on the late addition hops since they still have not had the time for much of the isomerization to occur. I figure that the modeling comes close enough to my sensory perception that it really isn't worth me chasing it any further.

Realize also that the IBU calculation is only an estimation of any real result. I like to think of it as the disclaimer in books and movies "any resemblance to any actual person or situation is purely coincidental."