I am making a b-day cake this weekend (10, 8 and 6) for my son's girlfriend, (this will be my first b-day tiered cake outside of my Wilton Classes). She wants each cake stacked directly on top of the other and really doesn't want the sps (I am going to discuss this with her mother to see if I can change her mind on the sps). In the event that I can't use the sps can I simply put each cake on it's respective cake boards and then use a large sharpened dowel to put through the center? Should I use extra dowels in the 10" to make sure it can hold the other two?

YES!!! You need to support all cakes with dowels.... and then drive one...I use two through the middle of all.

Does this girl know much about cake decorating ? since she's telling you how to do it ? Or maybe she does not have a clue, but just loves to give you orders on how she wants it done not thinking of what can happen if it is done her way ? Let her make this cake.

She needs to know that the weight of the upper tiers will crush the bottom tier without some type of support. You may offer straws or wooden dowels to see if she prefers one over the other. It may just be that she doesn't like column-size holes in her cake.

It's the column sized holes that she objects to. She is worried that she won't have enough cake if I use the columns. She is having 50 people and I have tried to reassure her that she will have plenty of cake even using the columns.