[ESS] ESS with Multiple Inferior Processes

[Alan Lue]

How does one select which inferior process an ESS buffer is bound to
when running multiple ESS processes?  To illustrate:

(1) C-x C-f [filename].R

(2) M-x R

(3) M-x R

Now you have inferior processes running in buffers *R* and *R:2*, but
commands sent from [filename].R go only to *R*.  How do you make emacs
send commands to *R:2*?

Section 6.1 of the ESS Manual says that ESS[S] handles the "ability to
switch between processes which would be the target of the buffer (for
the above)," but I don't see any further mention of this.

Alan