@HonestAbe1809
Here is the city facing west. Riverfront Square is between Busch Stadium to the left and Kiener Plaza Park to the right, so RS and Busch are directly across the street from each other.
This hypothetical expansion is taking place in 2006. They can simply build walkways above the street connecting "Old" Riverfront Square with "New" Riverfront Square. And since they don't have to build up to the stadium they can simply gut the building and use the outer walls as the framework of the new expansion. Waste not, want not. There'd just need to be some tinkering to provide a permanent roof to the new theme park expansion.