How do I create an Expense sub-account?

[Steve Kelem]

Hi. I'm trying to model my kid's finances within my gnucash file.
My thinking was that I could model it all in one file, and my kid hasn't
shown any interest in his own finance, other to spend it as soon as he gets
it. I also figured it would be easier to have his account as part of my
gnucash file so that accounting for transfers between the accounts would be
easier in one file than in two separate gnucash files.

I'd like to set up the gnucash accounts hierarchy as:

Kid1 (type Asset)
+ Kid1 Assets (type Asset)
+ Kid1 Expenses (can't set to type Expense!)
+ Kid1 Income    (can't set to type Income!)
+ Kid1 Liabilities (type Liability)
Assets (my assets, existing)
Expenses (existing, mine)
Income (existing, mine)
Liabilities (existing, mine)

The bottom 4 already exist and have lots of sub-accounts.

I was able to create the Assets and Liabilities sub-accounts, but not the
Expenses or Income. When I tried to create the Kid1 Expenses and Income
accounts, the Edit Account's Account Type choices are only Bank, Cash,
Asset, Credit Card, Liability, Stock, Mutual Fund, A/Receivable, and
A/Payable.

Is there a way to create this new sub-hierarchy with those account types?

Thanks,
Steve