Do you not have a detailed income statement? Can you not obtain a TB from whomever drew up the AFS?

If not then you need only use the Income Statement, Balance Sheet and Notes

If you do not need comparative figures, then you just post the balance sheet.

If you do need comparative figures, then post all of the balances in the income statement, all of the balances in the balance sheet excluding retained income, plus the retained income / loss balance at the end of the preceding year.

In both cases there is no contra account required.

Trust investments are monies held in trust for clients, presumably banked. It is off-set by the Trust Creditors account.

I don't understand why you don't have access to a trial balance. The AFS of attorneys with trust funds must, like estate agents, be audited (as opposed to a review) and it's inconceivable that they can't provide you with a Trial Balance. Similarly, to comply with law, you will need the detail makeup of the trust investments and trust creditors.