You couldn't decide whether to fuck Gracie's pussy, or butthole, so the logical option was to do both as you use your shapeshifting to split your penis in half, until you had two of them which would make it easier for you to do. You place your first penis in Gracie's butthole, and the second penis in her pussy.
Sometimes adding extra body parts to your body hurts, but the pain goes away after you cum, or when you decide to shrink back into your body as you started humping Gracie multiple times, until you both would cum while you were in bed. You could feel the excitement in your own body build up while you increase the speed, and then you both finally came as you fill both of Gracie's holes while you also pull out, and were still cumming even with your two penis's leaking dozens of drop.