@m501c3 

"Your recommendation not to use sub-accounts presents a few problems I cannot figure out, which is that (1) securities purchased from the Schwab account show up as Expenses in reports such as Statement of Financial Position, and (2) money markets sold show up as Profit, even though it's just the principle." 

After the transactions have been downloaded, you can select them and then 'Update' them.  Select the Schwab parent account under the 'Category' drop-down menu.  That will record two offsetting transactions under the Schwab parent account.  Or, you can 'Exclude' these transactions.  Since these types of transactions are offsetting to the parent account, there's no need to make an entry for them if you're not keeping sub-accounts.