For wellbore fluid treatment, sliding sleeves deploy on tubing in a wellbore annulus. Operators deploy a plug down the tubing to a first sleeve. The plug seats in this first sleeve, and pumped fluid pressure opens the first sleeve and communicates from the tubing to the wellbore annulus. In the annulus, the fluid pressure creates a pressure differential between the wellbore annulus pressure and a pressure chamber on second sleeves on the tubing. The resulting pressure differential opens the second sleeves so that fluid pressure from the tubing can communicate through the second open sleeves. Using this arrangement, one sleeve can be opened in a cluster of sleeves without opening all of them at the same time. The deployed plug is only required to open the fluid pressure to the annulus by opening the first sleeve. The pressure chambers actuate the second sleeves to open up the tubing to the annulus.