It depends. Usually, they can, but some spin-offs are made WITH the Main's ideas and world, but on a completely different 'strand'. Sometimes the creators may decide to link them later, otherwise, I'd guess it's safe to assume that they usually are. A prime example of a successful one was the sitcom Rhoda. Rhoda was a character in the Mary Tyler Moore Show.
Law & Order
Yes, There's the spinoffs.
Probably not as the main story already ended and any subsequent series may be spinoffs or to fill the gap that the original series may have left because of differences between the anime and the light novels.
Tales from the Crypt
A blowout coil connected in series with contactor's auxiliary contacts that shunt around the main contactor contacts. The coil is out of the circuit when the main contactor contacts are closed and in the circuit when the main contactor contacts are open.
When "Next Generation" and the other Star Trek spinoffs came along, fans started referring to "the original series" as TOS.
DQ IX is the 'newest' main series game, Dragon Quest Monsters Joker 2 is the newest of the spinoffs. The recent DQ VI release is actually a re-release of an older game.
There are Seven series all together. But then there is also spinoffs like the animated cartoon and movies. Hope it helps!!
series
Home devices are connected in parallel and not in series.
Inductors are connected in series in order to increase the inductance in the circuit.
the main switch is connected in the center of the panel