Harlikoofar base camp is on opposite direction of Rattu.
Your rout will be like this, Islamabad--Astore (By Road)-------Tarashang (By Jeep-2 hours)....Rupal Village (Trek--3 Hours)..........Harlikooar Base Camp (Trek--3 Hours). I beleive It doesn't lead to Shoutner, It goes to Other face of Nanga Parbat.
On the other hand its for shore there is a way from Astore to Shounter (Nelum Valley) you need to trace it.