Why were VC and PMS merged?

[emo samurai]

They each seemed to be doing perfectly well (better) by themselves. They both had their own coherent narratives and possibilities of future storylines, and sales seemed to be doing well.

[Adam_Arnold]

I've answered the question a couple of times in the Q&A thread, but the most recent was just two weeks ago here:
viewtopic.php?f=72&t=2383&start=435#p524284

What was your reasoning for joining the two comics in the first place ? I can't be the only one who was pretty disappointed when you squished them together - certainly to the detriment of the Paranormal Mystery Squad, which had so much more scope for stories than those vampires. Then you gave us that extra stuff with Heather...

The plan was to always have the Vampire Cheerleaders and Paranormal Mystery Squad casts crossover in the third story arc, if we ever got to it. That was a given and why we seeded appearances by the casts into the stories from the beginning. The "Vampire Cheerleaders Must Die!" story was intended (and written) to be a Paranormal Mystery Squad one and was going to run on PMS's website. Vampire Cheerleaders was going to be turned into "Vampire Cheerleaders Presents" with Lori Thurston as a Cheerleader Camp Councilor in a Vampyra-type "horror host" role with the first story being "Frankenbitches" and a later one being "Hoes From Hell."

There were two problems:
1) It cost too much to have two different series running with two different production teams. At that point, we didn't have enough ad revenue, so we still had to rely on print and ebook sales to at least break even on the production costs.
2) Vampire Cheerleaders' website was getting 3000 more hits than the PMS site was at the time. (Fun fact: Shiei was originally meant to be the artist on both VC and PMS, but production delays resulted in Comipa and Ian taking over PMS. Had that not happened, it likely would've been better received.)

When the decision was made to merge the two series together, "Vampire Cheerleaders Presents" was shelved, but the "Vampire Cheerleaders Must Die!" script was already completely written. So that entire PMS-centric story stayed largely untouched... except the ending, which was revised to be about Leonard..

The story arcs that were in the planning stages to come after "Vampire Cheerleaders Must Die!" would've had a mix of the two casts interacting together.

But yes, Paranormal Mystery Squad was always intended to have the "macro" story that tied all the various other parts together.