How do I go about attaching edible pearls to the sides of a cake? If I just push them into the buttercream, I am afraid they would fall off as they sat on there.

Royal icing or Edible glue .

if the buttercream hasn,t crusted. the pearls will be great. the buttercream will be the glue.. if crusted.. just dab of water.. hth

Piping gel and a pointy paintbrush.

I heard that using royal icing to attach them, the icing would interact with the fat in the buttercream icing and they would fall off. Anyone heard anything like that?

I dunno. But I can't be bothered to make a batch of RI for something like that.

ditto. Just stick the pearls on before the bc crusts.