If the property is sold at a sheriff's sale, the owners can bid on it if they have the money to do so. In many cases the owners will be allowed to credit bid, which means that they only have to come up with enough free cash to for the other half of the property.
You need to realize that a partition action is complicated and the nature of a sheriff's sale often makes it difficult to get full value for your property. You might consider mediation to try to reach a settlement. If that won't work, make sure you have a good real estate attorney handling your case.
Next time (if there is a next time) that you buy a house with other people, make sure you have a written agreement that outlines how the sale of the house is to be handled if you every want to dissolve the arrangement. Enforcing such terms is far easier to handle than what you are now facing.
You can reach Harkess & Salter LLC at (303) 531-5380 or info@Harkess-Salter.com. Stephen Harkess is an attorney licensed in the state and federal courts of Colorado. This answer is for general information only and does not create an attorney client relationship between Stephen Harkess or Harkess & Salter LLC and any person. You should schedule a consultation with an attorney to discuss the specifics of your legal issues.
I agree with Mr. Harkess and would add that a partition action is expensive, time consuming and usually everyone loses. Consider what both parties think they will lose right now if they give in to the other's request and then multiply it by two or three (that is just an example, clearly I don’t know exactly how much you would lose in this transaction). When real estate deals go bad, they generally go bad for everyone involved. If you are able to come to an agreement through a mutually agreed upon attorney or mediation, likely both parties will have to give more than they want to, but ultimately you will all come out better than if you go through a court partition. You should consult a local attorney to make sure you are addressing all relevant issues. Good luck to you.
Disclaimer: This answer sets up no attorney/client relationship. The information provided here is done so as general information only and is not intended as legal advice.