Correct... partially. You are correct in the sense that the only apparent change will be with Cleavon when you are talking about the lost love .Is there a scene with her "son" in this update so that we need the Ipatch?
Edit: we don't need to wait for an updated Ipatch for this version because there is no scene which would require it.
Also, given the way Zorlun built his game, and I build my patch, when the moment comes for 3.07, the incest patch for 3.07 will basically have inside also the one for 3.06a and previous ones.
At the same time, if you had 3.05 with the incest patch, overwrite it with 3.06a, and then go back to load an old save from a point in the story before the update 3.06a, it is not sure how it will react, it may work fine, bring you a bit back compared to where you were, or throw errors.
The only extra thing added in the last versions of the incest patch is a variable, because bibfoc needed it for one of his mods, but still, the compiled rpy are a bit different, so I cannot guarantee anything.