Introducing Cats

I am moving in with my boyfriend. He has 2 female (spayed) cats that are mostly indoors, approx 12yrs old. I have 4 male (neutered) cats that are indoor/outdoor (ages range from 3 yrs to 11 yrs). Their personalities vary significantly. I am trying to make this move as stress free as possible for all concerned and would really welcome some tips on how to go about introducing everyone.
   
THanks

I am moving in with my boyfriend. He has 2 female (spayed) cats that are mostly indoors, approx 12yrs old. I have 4 male (neutered) cats that are indoor/outdoor (ages range from 3 yrs to 11 yrs). Their personalities vary significantly. I am trying to make this move as stress free as possible for all concerned and would really welcome some tips on how to go about introducing everyone
   
First: Make all cats indoors-only. They'll live longer; they won't pick up parasites or get into fights; they won't get chased by dogs or hunted by coyotes (which are all over the country now, even in Maryland); they won't get hit by cars.
   
Use Revolution on all cats monthly to prevent fleas and parasites. Expensive, but worth it.
   
At least all the cats are spayed. 6 is going to be a mob...
   
Start this 6-8 wks before you meld households.
   
Get some extra cat beds or blankets for both houses. After the cats have slept on them, switch the beds so the cats smell each other via the bedding. Do this week for several weeks.
   
2 weeks before you move in together:
   
Take your cats over to his house in carriers. Put the carriers on the floor and let his cats investigate them thoroughly for a few hours. Don't take your cats out of the carriers. If no hissing happens, or the hissing trails off after a bit, then let them out to meet. Prevent fights.
   
Take your cats home, then repeat this process every few days. See how it goes. This may soften the blow all around when they find themselves together.
   
When you move in together, keep an eye on them & be prepared to have to separate them now & then when tensions run high.
   
Make sure everyone has a place to get away from the other batch of cats.
   
Cat politics can take 3 days, 3 weeks or 3 months to play out. Don't be surprised if at least a couple of them never get along.
   
Much of this is playing by ear. Rule of thumb: If there's no blood, then the situation is normal.
   

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Okay, I'll venture some thoughts.
   
FIRST, regardless of how things work out, Boyfriend HAS to get Girl spayed NOW. At minimum, it may calm her. She's going hormone-crazy every month, & this makes any cat testy. It could make her more friendly & approachable.
   
Since she's not fixed & expecting to have sex every month, she could be considering Boyfriend her potential mate, even tho he's not a cat - they get funny ideas (that bull moose in Maine who fell in love with a cow, he came to the farm every mating season). If she's not in heat, she could very well be less jealous of you & any other person or pet.
   
It is also cruel to leave a cat to go into heat every month for no good reason. So, right now, Boyfriend must make an appointment w/the vet & get her spayed. And spaying Angry Girl may just make this easier.
   
Girl being standoffish & easy to offend is normal for former ferals. They also tend to be more suspicious of everyone, incl. other cats; quick to take offense & unpredicable in their responses. Likely only time will cure this.
   
The real worry is that Boy doesn't have claws, which puts him at an extreme disadvantage, esp. since Girl's a reformed feral who can revert to feral in a fighting situation (this is natural). If she gets particularly nasty, he couldn't respond in kind & make her respect him properly.
   
A solution: buy Soft Claws to apply to Girl's claws, to reduce the damage she can do to Boy & people (plastic covers for claws, multiple colors, see Amazon for pricing & info.). They glue onto the cat's claws & are replaced periodically.
   
You can try is to introduce them to each other first by long-distance & then in person over weeks; this could shorten the adaption. (Realize that cat politics are unpredictable; 2 strange cats in a single home could maintain hostilities for 3 days, 3 wks, 3 months, or longer.) This process is best accomplished over a couple of months bef. you move in together.
   
(One possible help is that the new apartment won't smell like either of them, & neither will be in their territory. Neutral territory is less defended.)
   
You'll need a cat tranquilizer; it could help. Try Feliway (aerosol spray); it uses cat pheromes to calm, see petstores or the vet; also online, incl. Amazon.