Im happy to help!
I would definitely come back on Tuesday to do all the other exhibits and rides. Happy Harbor for your daughter could take hours! Theres alot for her to do including rides for little kids. Her cousin will love Manta. Its such an awesome coaster. There is an aquarium at Manta that your young daughter can visit while her cousin rides Manta. Alot of cool fish, Stingrays and even an Octopus!
You could fit the Dolphin feeding in on Monday if you choose. If you get there at 9am opening, you could shoot straight over there to feed dolphins. Im not 100% sure when that opens but it should be 9:00am when the park opens. The dolphin Cove is right next to Blue Horizons, so it will be an easy walk to the 10:00 show if you choose to go that route.
You had a question about Pearl diving. Pearl diving is located right outside the Sealion and Otter stadium. Also near the Pets Ahoy Theater. For a fee, you can pick an oyster at the bottom of a tank and there are 2 or 3 divers that will dive down and pick up the oyster for you and bring it up to open it. You get whatever is inside. Each Oyster is guaranteed to have a pearl. Sometimes if your REALLY lucky, you get two pearls inside the oyster. There are different types of pearls too. Some rarer that others and some more valuable than others. But I believe its all the same cost for an oyster no matter how rare the pearl or if you get two. Its cool to check out. And since its close to two show locations, it may be something your interested in doing before you see Clyde and Seamore or Pets Ahoy.
Hope you have a great time! Let us know how your trip went when you return!