You mean sub-groups in the FA account groups? Put the 3 digit accounts to be the sub-groups of 2 digit group? I started that way.  But would I see (somewhere) balances for my groups (sub-groups) of accounts?

I don't say I need subaccounts, I say I would call that. These subaccounts I've named them are actualy the accounts.
I'm asking all that because I still can't see  the all picture of the FA, it'll take some time. I've started from the GL because it's the foundation of everything.

I have another problem. We have account class that I could'nt recognize in the FA. It's purpose is ,I would call in english "calculation account class". The name of this account class is Opening and closing balance and profit/loss account. It's using when you opening new fiscal year, or opening new company, to put balances on the other accounts. Also, we are using this account for profit and loss and owner personal income.
My question is, which the class type it belongs? Income perhaps?

I can't see where are account groups in the reports or inquiry about GL accounts, or I'm missing something? Ok, I see that there are in the Chart of Accounts Report, but no balances for them.
Why is this important for me?
We use goverment authority obligatory 3 digit Chart of account, who belong 2 digit account groups and 1 digit account classes. But, in reality, I must use 4 digit chart of accounts. For results in the Balance Sheet and Profit and Loss sheet, we use 2 digit account groups. But, also need balances for 3 digit accounts.
So, my plan is that in FA I use account classes for my 2 digit account groups, account groups for my 3 digit accounts and accounts for my 4 digit chart of accounts. Actualy, I need another, I would call that, subgroup of accounts, because I need somewhere to see balances for my 2 digit account groups and 3 digit accounts (accounting regulations in my country).
Is this possible?
Earlier, I'd sent the administrators of the FA Chart of accounts (whitout 4 digit accounts) to put it in the download area, but I'm asking them to delay that before I dissolve this.