It's pretty easy to intimidate a little pup by mere physical presence. What I've been trying to make clear is that there comes a day when they are no longer tiny little pups and its not so easy to intimidate them into compliance.
I do not claim to be an expert on dobbies. Heck, I'm a self proclaimed expert on nothing. [
]In my experience however, with large breed, independent thinking dogs (german shepherds) there comes a time very early in their lives when you can no longer easily feed them together.
As the OP learned with one plate, someone is going to get pushy. I've watched litters I've fostered and they always ALWAYS get enough to eat, there is never a concern about where the next meal is coming from or when because I'm very consistent about feeding times. When they are first weened, it's pretty much ok for them to share a pan. Although with multiple pups its pretty typically multiple pans, but still not one for each pup. In my experience, around 6 weeks, some dominance is going to start peeking through. Not necessarily agression, but one pup might claim the entire pan by getting IN said pan and inhaling the food like a vacume cleaner. And quite often pups will eat themselves silly.....not actually needing that much food but wanting to insure that no one else gets it. Seems to be hardwired into them. But, I don't recall any growling at all between the pups....just pushiness. My last litter we had a little guy who was pretty passive about being shoved out of the way and very early on I started giving Mr. Ears HIS food in his own bowl in a crate. This allowed him to eat in his own time (he was a pokey eater and liked to savor his food) without any competition and without being shoved out of the way.
By the time the pups were placed however, I could line up six bowls side by side by side and each would eat from his or her OWN bowl without attempting to steal his/her neighbors and then go to the door to be let out. This was accomplished by my presence in the room, but also by gentle redirections to their own bowls.
But, the OP has the further complication of the terrier. Now terriers tend to be rather pushy by nature and want what they want when they want it. My advice on this one would simply to be not to allow the terrier in the room when the pups are being fed, UNLESS you have the time and energy to train her to respect their food. She might be tenanious, but, pretty soon those pups are going to be a whole lot bigger than she is and won't put up with her interference, and as you've already seen, they can be pretty darned rude about that. You don't want the terrier to be hurt down the road.
In my multi dog household, everyone eats separately. I know for a fact that Tyler and Sheba can eat side by side without issue, but if I were to introduce Theo to the mix, there might be problems. Theo has "little mans syndrome" and likes to prove that he's bigger and tougher than anyone else, despite being a little spit, in gsd terms. Yet Theo is not a huge eater and can typically take or leave food. But the competition angle turns him into a pushy little jerk.
Each and every one of my dogs will jump through hoops to please me, but, when it comes to food, it's not so easy for them to remember that. I could enforce the rules and feed side by side with all six, but that creates a less than peaceful situation at meal time for them and for me. It is not essential for them to stand next to one another to eat...there is plenty of room in the house, and there are plenty of quiet and peaceful crates for them to enjoy a meal without even having to think about "defending" their food.
I have a boy from the last litter. Tyler was placed in a home that I really screwed up on. I'm not often fooled, but when he came back two months later, he was in terrible shape, physically and mentally. Because of that situation and my own guilt, we worked doubly hard with Tyler to help him develop his self confidence, to help him to feel special. It worked and Tyler can go anywhere and do anything, including the annual MS Walk where this year a volunteer remembered him from last year, right down to his NAME and the color bandana he wore, to working with the elderly in a nursing home/assisted living setting. Tyler is no more special than my other dogs, but he got a good deal more one on one because of my guilt and has become an absolutely stellar animal. The one on one time is crucial, even when you have a pack as large as mine.
OP, please remember that as your pups grow. Find time to work with each individually and help both of them shine. It's really hard at the end of a work day, on the too short weekends, to find that time for each dog, but we've found that it's essential to them being all that they can be. Tyler gets no less one on one, but we've found that we really MUST increase the time for the others as well. And not just group romps in the woods, but the ride into town, the trip into the hardware store, etc, so that all of them have the chance to shine. There are days when it feels like my life has completely gone to the "dogs" but what wonderful rewards when you have six german shepherds who can go anywhere and do anything. Individually at this point still...because more than one leads to a bit of competition.....but, we're getting there. The work and the training never stops no matter how old the dogs are....there is always something new for them to learn or to experience. Just like with people....we can never stop learning or we stagnate.
You've got your work cut out for you, but much of it is a time thing.....be sure that you make time to work with or play with each pup one on one and to develop an individual relationship with each and the rest will fall into place. Yes, you need training classes, and yes you need professional "help" to get your two to excell, but the biggie is time. Find it and everything will be much easier, despite having two from the same litter. You wouldn't be here if you didn't want to learn and grow along with your pups, and despite the crankiness you've seen here, we are all willing to do whatever we can to help you on your path.