Please refresh my memory. I am running on the idea that the GR is 9-10 months old? That screams SSA moreso than puppy pass. The puppy pass usually disappears at 4.5-5 months old. And then it is not a bloody scrimmage. it is usually a snarl and maybe something that sounds terrible but no blood whatsoever. The behavior of the puppy on the receiving end, might be what you described.
Frankly, I think that so long as you have two bitches in your home, you are going to have a heightened/charged atmostphere. Some bitches, once there is blood, look for any opportunity to get to the other bitch. Some bitches can go several months, and then someone walks too close to the other, brushes them the wrong way and someone punishes, someone retaliates, and it is on. Sometimes when a dog is in attack mode, and are separated, they will redirect that aggression on the person separating, or on whatever walks by. Living with two females that do not get along is not for most pet owners.
My vet has Jack Russels, and every so often he has to come in and get antibiotics, etc, when they get into it. Someone who has one of my boys, has two bitch littermates, and their dam; every so often they tussel, and every joins in. A tiny dog would not have a prayer in that scenario.
I know this is not what you want to hear. But if the bitch pup goes away, and you give your girl a few WEEKS to get normal again, you can probably have the same harmony you had in your home before this issue cropped up. If the bitch pup stays, it is probably just a matter of time, regardless to how many behaviorists, trainers, NILIF, etc. that you try.
Every time you bring a bitch into a home with another bitch, there is a possibility that they will have to be totally separated down the line. Some breeds are worse for SSA. They say that dogs fight for breeding rights, bitches fight for breathing rights. Personally, I think you can generally get two dogs to live together. Some people will even give the advice to sit back and let them figure it out. Don't do that with bitches, because you might be burying one and having to put the other down.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC