Sugar in a Wheat Lager?

[Protos]

Gentlemen, please help me to formulate a recipe. I'm planning to brew a clone of a commercial light lager which contains 30% of unmalted wheat and an unspecified amount of sugar. Original gravity is 12/1.048 and ABV is 4.5%. Given the figures I'd deem the use of sugar unnecessary but it's listed in the ingredient list of the original. The original I'm planning to clone is not a dry or spirituous beer, rather it's on the sweeter side.
My question is, at what stage and in which quantities using of sugar is appropriate in such a recipe?

 

[Soulshine2]

have you run your recipe through a brew calculator app yet?

 

[Protos]

Sadly, I'm not too much familiar with brew calculators. With them, I do just the simplest things, like calculating IBUs or gravity corrections. More complicated math still remains out of my range.