I am making this wedding cake and I am not sure of how to make the fondant ribbon. I don't know if I should do it right on the cake using a 50/50 mix. I am confident of making the calla lillies but the ribbon I am not. If there are any other design elements that I am missing please let me know, as sometimes I can be a dunce. TIA

I would use straight fondant. If you deliver already stacked, then just cut your ribbon(s) .....dust lightly w/cornstarch &/or powdered sugar & roll up for easier handling.