Can I file my return and my son's return on the same turbotax account, or do i need to make a separate account for each of us?

No, you need to start a new account.

If you still want to start another return in TurboTax Online, here’s what to do:

1. Sign out of TurboTax Online.
2. Select the TurboTax Online product you want to use for the second return and proceed.
3. On the Create your account screen, set up a new login for the second return.
   • You can reuse your email address if you want to receive e-file notifications for the second return.
   • Up to 5 accounts can be tied to the same email address.
4. After you've created the new account, you can start working on the second return.

No, you shouldn't file your son's return on your same TurboTax Online account. Never start another return by going back and overwriting everything in the return you just filed. This will replace your info, which means you won't be able to retrieve your return later. Please refer to this TurboTax FAQ below for how to start an additional return in TurboTax Online: 

https://ttlc.intuit.com/replies/3288574