var doc = app.activeDocument,
sel = doc.selection[0],
_lines = sel.parent.lines,
txfm = sel.parentTextFrames[0],
gb = txfm.geometricBounds;
for(var i =_lines.length-1;i>0;i--)
{
var nextframe = txfm.parentPage.textFrames.add({geometricBounds:[_lines[i-1].baseline,gb[1],_lines.baseline,gb[3]]});
nextframe.textFramePreferences.firstBaselineOffset = FirstBaseline.LEADING_OFFSET;
txfm.nextTextFrame = nextframe;
}
txfm.geometricBounds = [gb[0],gb[1],_lines[0].baseline,gb[3]];
for(var i =sel.parent.textContainers.length-1;i>=0;i--)
{
sel.parent.textContainers.duplicate();
}
for(var i =sel.parent.textContainers.length-1;i>=0;i--)
{
sel.parent.textContainers.remove();
}