R. L. Stine's The Haunting Hour/WMG

Sara (from The Most Evil Sorcerer) is the ancestor of Alice (from My Sister the Witch)
Quite ironic since Sara hated magic and yet Alice became, well, a witch. This could also mean that

The Show seems to take place in a rather Crapsack World
Judging from the suspiciously similar neighborhood's in "Really You", "Game Over", "Catching Cold", "Brush with Madness", etc you can probably assume that all the episodes in this series (except maybe "Scarecrow") take place in the same universe. So if you think about the main characters live in a world full of ghosts, aliens, monster clowns, etc. that's pretty creepy!
 * Unless you count "Scarecrow" as the end of the world and takes place after the (possibly not for a long time) episode.