The law regarding discharge of tax debt can be tricky. You need a bankruptcy lawyer that is familar with the tax rules. You could also have a tax attorney work with your bankruptcy attorney.
Any individual seeking legal advice for their own situation should retain their own legal counsel as this response provides information that is general in nature and not specific to any person's unique situation. Circular 230 Disclaimer - Advice given in this response cannot be used to eliminate penalties with the IRS or any other governmental agency.
You want a bankruptcy attorney who is familiar with priority debt. The rules on income taxes are pretty straight forward. If the return has been filed more than 2 years ago on a tax year that is more than 3 years ago and the tax was not reassessed within the last 240 days, it is subject to discharged.
In English, if you filed the returns on time and the tax was due for tax year 2006 or before, then it is dischargeable. Your attorney has no control over this and filing the petition any other way does not change whether the debt is or is not dischargeable. Just make sure to check with the IRS after discharge to get an accounting.
This is a basic bankruptcy issue for any competent bankruptcy practitioner. In my opinion, all you need is a competent bankruptcy attorney. I recommend that you consult with an attorney who represents debtors in chapter 7 cases on a regular basis.