I've been working with Steam to update the company type from Individual to LLC through support. Annoyingly, support said:

In most cases, we don't change the legal name or legal form of an entity. Instead, we find the cleanest path is to create a new partner account and transfer the apps to the new account.

There are a few steps to follow for creating a new entity. Please follow these steps carefully.

Step 1) You will need to onboard Steamworks under the new partner legal name and provide banking and tax information for that new partner. Please do this under a different Steam user account that is not associated with any Steamworks accounts currently. Create a new account if you need to. Onboarding a new partner account requires paying the Steam Direct fee.

Step 2) Once you have finished onboarding the new account, you can transfer the apps to the new account using our app transfer tool. Sales before the transfer date will be paid to the old account, and sales after the transfer date will be paid to the new account.

If you believe that your name change can be accommodated because it is the same legal entity, form, and tax ID, then please explain the circumstances.

This is annoying, because I already had to create another account to sell games as an individual in the first place... but I don't really have a choice in the matter I guess. I'll have 3 Steam accounts after I follow their steps.