Sunny the scardey cat

Looking for advice. Been trying acclimate 3 new cats in my home with one settled male cat. 2 of the 3 my gf brought have settled in fine, but Sunny, she's been a handful. She's never learned how to mingle with her previous kitty roommates (one male, one female) who moved with her, and now she's got it worse with a new setting and another boy. Sunny only feels comfortable hiding or with people... Which would be fine if she didn't finally learn to explore only to find herself trapped far from the cat box and so nervous she refuses to move from a hiding spot and finally craps herself. This still after having done the sequestered room with her own supply gig (twice) for 3-7 days thing. She's desperate to avoid the other cats, hisses, growls, panics and hides. She prefers to hide in the utility room with the food and litter, but we're happy to see her venture out despite accommodations we've made for her (cat tree, etc). But when she comes out she eventually panics and hides in a bad place. Please advise.

Sometimes 3-7 days is not enough, some cat introductions take weeks, months, or even (I am sorry to have to tell you) over a year.

What I'd recommend it reading these two articles, and then reintroducing her to all the cats, very very slowly, only moving on to the next step each time once she seems completely comfortable. Once you have read the articles, let us know if you have any questions- we are here to help!

http://www.thecatsite.com/a/the-ultimate-yet-simplified-guide-to-introducing-cats

http://www.thecatsite.com/a/introducing-cats-to-cats 

On another note, one litter box is REALLY not enough for 4 cats and I'd add a few more to try to make sure that no more accidents happen.

Ohno, there's three cat boxes, lol. Thanks, I'll read the articles and let you know. 

Meantime, open to any further musings or ideas. We're even trying those plug-in pheromones.

Thanks!