Radial engines do have one 'master' rod per throw. The other rods on
that bank of cylinders are connected to journals (lower end bearings)
on the master rod.
FWIW the master rod looks kind of like a banjo with the other
connecting rod lower end bearings arranged on an arc equidistant from
the main journal on the crankshaft. Each of the other connectings
rods is clamped about its own journal. You can see the sides of the
bottom of the master rod has to be split so as to hold the journals
between its two parts. As the crank rotates the bottom end of the
master rod goes around with it, dragging the other rods along. Of
course all the pistons go up and down and push the whole assembly
around. If you think this is complicated, the P&W R4360 has four banks
(a four-throw crankshaft) with 7 cylinders per bank. Your local
library probably has a book in its files that wll explain the matter
in more detail, hopefully with pictures.
Walt BJ