But still, I think it's worth the expense of consulting a local tax pro before you do anything.
Who actually paid for the property, claimed the rental income and expenses, paid the property taxes, mortgage interest, etc.? Then who actually pocketed the gain? That's who pays tax on the gain.
I was in a similar situation with one of my rental properties. The only reason my parents were on the loan and the deed, was so that I could get the loan. I paid for the property 100%, plus all the property taxes, mortgage payments and interest, and I was the only one to report all this on SCH E. Therefore, upon disposition of the property I am the one to reports the disposition, and I am the one who pays taxes on any taxable gain. While my parents did have a "legal obligation" to pay for the property and it's associated expenses, they never "actually paid" a dime. So I am the one who has to deal with it tax-wise, and not them.