Well, you can just move your projects to smooth dirt.
First you are gonna wanna open file explorer or whatever it's called on your OS.
Then navigate to
WhateverHarddriveSteamIsOn:\Program Files (x86)\Steam\userdata\WhateverYourUserIdIs\394690\remote\Condos
in here you will find the condo saves which dictate where your items are.
So if you wanna say move your underwater condo data to highrise then you can move your already existing highrise save to another folder on your pc where it can be kept as a sort of extra save incase you wanna make a new project.
Then you just take the folder called "C_Underwater" and rename it to "C_Highrise"
Now you can load up your Highrise condo and have it load the object data from your Underwater condo:
Beware that for some odd reason when you load your condos the game will make a copy of whatever condo save you changed the name of and name it what it originally was called.