I am behind on property taxes due to two of the owners whose whereabouts are unknown. The property is up for sheriff sale in 6 weeks

If the property is up for sale due to unpaid taxes, it sounds like the taxes have been delinquent for several years.  Taxing authorities are usually agreeable to payment plans.  You should contact them and ask what type of proposal they will accept.  Keep in mind that the taxing bodies can file suit against you personally and get a judgment against you for the unpaid taxes.  That would allow them to pursue your personal assets, not just the property in question.