Your site is always so fun to visit! Great McD cake and your sister did a fine “first run” wedding cake, as well. I think someone already mentioned using wooden dowels to help support a multi-tiered cake (you can even use straws on smaller tiers, in a pinch). You might also try a cardboard round on the bottom of each tier for support (I’ve only tried stacked tiers, not sure about the “pillars” like your sister used).