FTX.US has Subaccounts to allow you to split up your positions
To manage your Subaccounts, go to https://ftx.us/subaccounts.
There you can create new Subaccounts, switch which Subaccount you're using, and transfer funds between Subaccounts. You can also toggle which Subaccount you're currently using by clicking on your profile name in the upper right hand corner and clicking 'Subaccounts'.
When using a Subaccount, you can only trade with funds that have been moved to it. That means you can only trade on spot markets or convert using funds in the Subaccount.
Subaccounts are useful if you want to separate different strategies or traders; or if you want to isolate a particular position from the rest of your book.