First, because your other dogs have not attacked her back, do not assume they won't. Everyone has a tolerance threshold and you never know where that might be reached.
What I suggest you do is first off, never ever leave these dogs together unsupervised. Your little pom it sounds like is possessing you and wants you all to herself.
Next, here's a little something you can do: Google NILIF (nothing in life is free) and start implimenting that with her. Then while you're not giving her excessive or heaping piles of free attention, you keep the other dogs seperate from her. Take her with a leash on and enter the same room as the other dogs. For 30 seconds, in the other dog's presence, start feeding her pea sized treats of high value....chicken or steak. Toss some to the other dogs too. Tell her how special she is and lavish her with attention. Then remove her from their presence for 30 seconds and ignore her...no special attention, no treats. Then re-enter the room where the other dogs are and repeat. Do this several times a day...just a 3-5 minute practice with 30-60 second inervals of each...the coming and going. I'd keep her seperate for a week or so from the other dogs when you're not working with her directly. Then when you try again to have them together, watch her closely and assess. Do not, under any circumstances punish her or speak harshly if she is getting snarky with the other dogs. It will make her worse because she'll associate them with punishment. You want to associate them with good food and affection/attention from you. In other words, when those other two dogs are around, good things happen. It's good news that they're around close.
When you're not doing a session, don't carry the "cold shoulder" to an extreme. This could cause a lot of stress in her. But try asking her to sit or come, shake paws, something just before you want to have a little love session. Save the best stuff for those times you're working with her and the other two dogs.
And above all, this is never a sure fire thing. You will always have to supervise. But it may make her look more favorably upon the other dogs and also teach her that you are the leader and make these decisions, not her. You're the leader because you're the one who controls the things she likes and needs; food, attention, affection, toys, going for walks, etc. Her behavior earns her these things.