How to sell 5% ownership stake in apartment building?

[Brent Seehusen]

Here's the situation:  There's a 32-unit apartment building originally purchased in the 1970's by three business partners.  As the years have gone on, those original owners have passed away and the building has passed down to their children.  Now some of those 2nd generation children are at an advanced age and passing away so ownership is passing to the third generation grandchildren, resulting in smaller and smaller ownership stakes for each succeeding generation as it gets split between more people.

One of the 2nd generation owners with a 5% ownership stake recently passed away, leaving 1.67% ownership to each of his three children (the 3rd generation).  It's getting to the point that these fractional ownership interests are too small and the beneficiaries would rather just cash out than hold for the long haul.  What are the options for liquidating these small ownership shares, assuming none of the other owners in the building want to buy them out?