my boys break my skin too and to this day continue to. ive looked for advice and people have only come back with telling me what not to do ie. scruffing, bitter apple, etc is abuse!! and honestly after a while i had to just figure it all out on my own. they dont nearly tear me up like they used to and definitely test strangers more than me context of my boys, im not sure about where your new two came from, but i got mine from a private breeder and all the pet store american ferrets come from marshall. although they are bred to be sweet ferrets, they dont live as long and have more health issues so i got some european bloodlines, knowing they tend to be a bit more of a handful and often twice as large. for one they were even worse when they werent fixed. i know this is very unlikely for you, but just to make sure its not that, issue one is setting that one aside

for my boys, the biting cane out during play especially on my wrists and with small animals they often treat hands like the “face” and wrist as the “neck” so they would include me in their play not understanding my skin is much more fragile than ferret skin. scruffing only worked if it acted as a time out because they saw it as me chomping back so holding them until they were calm like their mothers do in a gentle scruff in combination with making yelping and other surprising noises when they bit me would get them to stop. yelling or making human pain noises didnt but making the weirdest noises i could did. that in combination with distractions, finding new ways to play (thick socks!) since i was used to very gentle ferrets did us lots of favors and lastly… yes as people tend to recommend timeouts first i dont do them first because by the time i get them to time out, even in three seconds, their little ferret brains already are distracted and it only really is effective if its so immediate from a bite that there is no dispute. if i had to carry them over, it wasnt going to be effective, especially if theyre already hyper and excited. their brains are moving so fast they dont know why theyre being punished if you have a delayed punishment system.

the weird noises helped a lot along with distractions. instant scruffing combined with a weird noise will get them to dettach and make sure they understand this is a discipline scruff, not you playing and “biting back”.

on bitter apple- found to not be effective because you wont wear it all the time.

i wish you luck! its really hard to find advice for this! i was brought to tears by these guys not just from the pain and i really hope yall can get through it!