You can have fixed payments as long as your software will handle it.
The $10,000 payment example on the plan disclosure will show what the balloon payment will be based on the fixed payment and the $10,000 advance.
In the note itself you don't have to disclose the balloon payment. The note will say something similar to:
At maturity I will pay the entire outstanding loan balance in full.
You will have to be sure the "negative amortization" language is present if the fixed payment is not enough to reduce the balance.
Call your software vendor. I'm sure their customer service reps can help you set it up.
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The opinions expressed are mine and they are not to be taken as legal advice.