Mixing : Basic Mixing : Sends : Assign an Existing Track from a Send

Assign an Existing Track from a Send
Pro Tools lets you assign a send directly to an active Auxiliary Input, Audio, or Instrument track using an available internal mix bus. Note that the destination track must be set to either an internal mix bus or to No Input in order to be available for assignment.
To assign a send to an available input on an existing track:
1 On an existing track, click the Send selector and select Track.
2 From the Track submenu, select the destination track you want.
 
Pro Tools automatically routes the send to the input of the selected track using an available internal mix bus.