I'm pretty sue you can't use Ero attacks on them, and they just fly away when you win. I meant player victory. You can have it a chance that you can grab one before they escape, or all 3. For victory scenes, you have options. You can do the same they did (nipple onaeholes, fairy dildo, etc..), but in reverse, with the player in control.
Also, is there any other futa in the game? Rinny can grow one temporarily, but that's the only one. How about adding a 10-20% chance per nandit girl encounter that the she will be a futa (with victory/defeat scenes of course)?