Are you making the head with Rice Crispy Treats or is it cake? If it's the treats, then I would stick a few skewers into the bottom of the head and then push it into the cake.
If it's made from cake, I would push a sharpened wooden dowel from the top of Elmos head all the way thru to the bottom cake board. That will also help with stabilizing the tiers from shifting.
I hope that helps!
AThanks!! I've never really used rice crispy treats and te initial plan was to make it using cake. I'll have a look into rice crispy treats as well. Thanks again :)