Hi Julia ,
Here is what I normally do for my cakes more than 3 tiers .. Always centre dowel which is a rod wooden or metal whatever is available attached to the main board on which ur cake Wud be stacked . Then each layer is slided through the dowel .. Also each tier is also doweled and each cake has a cake board of its respected size . Between each board and the cake tier apply ganache or royal icing so it does not slide off . Hope this helps .
Shweta Somaiya
