Relay for Raspberry Pi?

Question

Raspberry Pi

We need a relay for RaspberryPi, preferably as in the figure, but with python control, so that output A can be closed by choice with one of the contacts.

Answer 1

The relay itself is a simple mechanism, applied current, it opened / closed, in this case, if the loads are small, such a multiplexer
will do. If large, then take such a module and connect the power section as shown in the figure, you will already have 8 channels
P.s. in fact, the power cable must be connected to the central input, since there are three power inputs for each relay

Answer 2

What is the load? Is the output current high?
There are a lot of options - from using just 8 GPIO lines to using 8 pieces of powerful relays controlled by the same lines and with a common input. The above is the correct relay module 8 indicate. If the load is even more powerful, then individually powerful relays.