One way is to append the reports to a horizontal list box:
Names Default To Here(1);
dt = Open("$SAMPLE_DATA/Big Class.jmp");
biv1 = Bivariate(Y(:weight), X(:height));
biv2 = Bivariate(Y(:age), X(:height));
New Window("Example", hlb = H List Box());
hlb << append(Report(biv1)) << append(Report(biv2));
You can also explore the power of the SheetBox() or "SheetPanelBox" display box types that allow for custom arrangement of other display boxes horizontally and/or vertically.