Corn Syrup for Italian Meringue Buttercream

[Cee]

Hello, I live in the Caribbean and we currently have a sugar shortage on our island. Specifically white sugar. I am looking for an alternative way to make Italian buttercream icing and am wondering how to use corn syrup in place of the usual sugar syrup. It is much thicker than the syrup used and has to be heated to add to the egg whites. Should it be diluted before heating or dilute with boiled water? Any ratio? Has anyone done this? I have made it with a brown sugar syrup, but we have a shortage of that too!