i would like to combine automated trading from QC with manual trading in one IB account.

Does this work? 

I have found in the documentation the following

By default, IB only supports one connection at a time to your account. If you interfere with your brokerage account while an algorithm is connected to it, the algorithm may stop executing. If you deploy a live running algorithm with your IB account and want to open Trader Workstation (TWS) with the same IB account, create a second user on your IB account and log in to TWS with the new user credentials. To run more than one algorithm with IB, open an IB subaccount for each additional algorithm.

In other words: I log into the account with a second IB user account. Then I can add manually positions AND the algo runs in parallel?

(I do not want to go into detail, why this makes sense… ;) )