I am making a coconut three tiered wedding cake. They want straight coconut filling (like the inside of a Mounds) I'm making this with coconut, sweetened condensed milk and a bit of Malibu Rum. 

Anyway-should I just do the filling on all layers(each layer will have 4 layers) or should I alternate with cocnut buttercream? I've never done a tiered cake with this filling and just want it to hold up.  Any advice?

Thanks!

I would alternate. Coconut is one of those things that not everyone likes. I like the flavor, but not the texture of actual coconut. Seems like the more you chew, the bigger it gets~ ya know? 

At least if you alternate it, the guests can scrape off the actual coconut and still have something besides just cake.

Mix one 14 ounce coconut that has been finely chopped in food processor and mix with sweetened condensed milk. This taste just like a filling in a mounds or almond joy candy bar.  Crushing coconut in food processor helps so coconut is not stringy.

i would do like jgifford suggests and use one generous layer of the coconut filling per tier and the others i'd want to do whipped cream or whatever icing you are already using --

and remnant is right on that you want it minced fine so it will cut and serve well without losing servings --

and i'd also check to see how much of this filling soaks into the cake and might leave the coconut drier and flakier than you intended -- remember wedding cakes need to be work horses with a good shelf life and still be nice & fresh & wonderful -- you might could get around this by a thin coat of icing above & below the filling if necessary -- 

i've never made it -- so i don't know -- just thinking out loud -- i use a cooked toasted coconut filling that does really well but never one like this

best to you