Ummm…Don’t you think it would be simpler to just be long 1 position and short none? There is no reason at all to do the other long and the short as it’s not going to give you any directional exposure and will cost you the spread.
So in Grid Trading, there must be 3 trades, either 2 positive longs or 2 positive shorts, to be profitable.
In ALL spot forex trading there must either be a long exposure to a short exposure to have any chance to be profitable (or take a loss).