Aggression of old ferret to a new one

Question
I have an older male ferret that came from a breeder, (has european bloodlines). All my other ferrets are male and the other 2 came from marshall's farm and never had aggression problems or biting like the breeder ferret. He has always been more aggressive and bites hard on people (sometimes drawing blood). I can't trust him not to bite anyone that is not me.
He used to live with 2 other ferret that were added in when he was 8 months and one when he was about 1 1/2-2 years old. I never had any problems then, he would bite them but nothing like what he does to the new baby.  Now he is almost 3 years old and one of his friends died.  A new baby was brought in and after isolation, i was not able to have the baby loose with the older ferret because he was so vicious toward the baby and the baby would scream and sometimes deficate and urinate.  The baby is scared of him if the older ferret is loose (he is brave in the cage and fights through the cage with the older ferret). The older ferret is focused on attacking the baby when he is out.  The older ferret still gets along fine with the established ferret he lives with. I have been swiching the older ferret between the cages so he gets used to the baby's scent around the area. Now the baby is about 3-4 months old and is bigger, but i can not let him out with the older ferret.  Is there any technique to use to try and get these 2 to get along, or am I doomed to always having to alternate outside playtime between the 2 ferrets?
I am considering getting another baby ferret so the new baby has someone to play with. My other 1 year old ferret gets along with both, but get tired after playing for so long, then the baby keeps bothering him because he is awake longer and more active. Do you think the older male ferret may have a better chance of getting along with a baby female ferret better.  This way I would only have to keep the 2 male ferrets separate or do you think i will now have 2 ferrets that i have to separate from the older male ferret.

Answer
We have come a long way in understanding ferret behavior....this said, we have learned that switching bedding etc is not the best way to introduce ferrets.  Ferrets are naturally solitary and not social.  Switching bedding and cages and playtime is great for social animals.  Ferrets see this as an intruder ferret that they can't get to.  They you let them out together and BAM the pent up anger begins.  
We sometimes see gender specific aggression in unaltered males and females.  I am assuming all yours are spayed and neutered.  Marshall ferrets are also bred differently and tend to be more docile so your non Marshall ferret is going to be a bit more aggressive.  I just wrote 2 articles for ferrets magazine covering these 2 issues - Biting is in the 2006 annual and Introductions is in Spet/Oct issue.  So your problems are reasonably common!  
Regarding the fighting.  Certainly be careful with the younger ferret until it is full grown (very soon) but there are going to have to sort it out themselves.  Everytime you break up a fight - the aggression will heighten next time.  Screaming is a natural response.  If your newer ferret is urinating etc I am guessing the older male has intact scent glands?  If so this is also not unusual.  A ferret without scent glands needs to make a smell too and often poop is the only way to go!  If the bting is happening on the neck and back then I really would back off and let the fight happen.  My worst fight ended up in a ferret with a 1 inch hole in his belly skin.  After a trip to the vet for stitches (the belly is not as protected) he came home and we let him go into the group.  That was the last fight between the 2 in question.  Now they share a food dish and play together.  My most aggressive ferret spend nearly the first 4 months here hunting down everyother ferret in te group = they learned to avoid him and they could run faster.  He eventually settled down and now there are 2 he seems to like and 2 that aren't afraid of him anymore.  Patience and an ability to not jump to the rescue are vital skills for you.  I don't believe that there is ever a time where ferrets can't work out the system and get along.
The final issue for the older ferret may be Adrenal Disease which can manifest itself through aggression.  He is 3 so it is a possibility.
If you get another ferret - the best way to introduce them all (after a quarentine period) is to take them all to a neutral place (somewhere they don't get to go often) and let them out.  When they are tired, bring them back to the normal playroom and keep letting them play.  Only break up a fight if someone isreally getting injured but also make sure you leave lots of places to ide so the hunted ferret can excape.  Bob Church's nest boxes are great for this.  Take a Rubbermaid tub (smaller type) and cut a small hole in one side then place a section of white plastic gutter out the hole.  This provides a dark and natural hide box as well as a safe place from as bully.
Good luck and let me know how it goes.
Ailigh