Selling Part Interest

Selling your part interest is the same as selling any other real estate.  You just have to find someone who wants to share the ownership with your brother and sister.  Or perhaps the two of them would buy you out, after an estimate of current value by a qualified appraiser.

Your other route is to force a sale of the whole property by going to court and requesting an order for "partition."  That's an expensive and unpleasant process, and seldom yields the true value of the property.  Not recommended!