Does sibling 1 have an issue with bad credit or low income? Why can't the sibling living in the house--sibling 1-- take out a mortgage against the home to buy out siblings 2 & 3. Essentially, the 3 of you would be selling the house to sibling 1.
You do have the right to force a sale under these circumstances. The sibling living there needs to be advised that if (preferably by an attorney who represents you and your other sibling) he does not agree to sell, you will bring a partition action in court to force the sale, and that you will seek attorney's fees from him for forcing you to bring the action. Usually, a letter like this will prompt him to see a lawyer of his own who will advise him that he has no case, and that his failure to co-operate will only make matters worse for him.
Additionally, as co-owners, technically, you each have the equal right to live in the home at the same time (which is why you can not force him to pay rent). You can ask that he voluntarily agree to pay rent if you agree not to force a sale or ask for rent until the place sells. However, he does not have to agree to do so. Sometimes advising of this, or if necessary, moving in, is enough to get things moving in the right direction, However, it can be very uncomfortible. Obviously, with family you would prefer to handle this with the least collateral damage as is possible.
I hope this answers your question, and good luck in resolving your legal matter.