Rdc = (1+Rfc)(1+Rfx)-1
Shouldn’t this work in any instance where you are forecasting expected return? You can either plug in your projected unhedged FX return or plug in your hedged FX return.
Theres also
Hedged ~= id + (Rfc - ifc)
Unhedged ~= rl + Rfx
I dont like the guideline answers tend to sometimes add (shortcut) and sometimes multiply. Especially with interest rate parity and foreign exchange things.