Can an InputAction have binding and compositeBinding at the same time ?

Hello,
I'm trying to understand the new Input System. In my case, I want to be able to select characters by left clicking them. If i have a character selected and I press on a different one, only the new character will be selected. But if I want to select more than one character, I just have to press "Shift" and the character will be added to the group.

To do this, I thought I could use only one InputAction with a simple binding and a compositeBinding. So if in my performed event, i just have to check if "Shift" was pressed.

It is possible or I have to create two differents Input actions ?

         _selectAction = new InputAction(
             type: InputActionType.Button,
             binding: "<Mouse>/leftButton",
             interactions: "press(pressPoint=0.01)"
         );
         _selectAction.AddCompositeBinding("ButtonWithOneModifier")
             .With("Modifier", "<Keyboard>/leftShift")
             .With("Button", "<Mouse>/leftButton");
   
         _selectAction.performed += context => OnLeftClick(context);
         _selectAction.Enable();
 
 private void OnLeftClick(InputAction.CallbackContext context)
     {
         //Here you check if the Modifier was pressed, is it possible ?
     }