Bonded Pair Swap?

Hello, I have been debating for the last couple weeks of switching my bonded pairs around. I am hoping to get input, opinions, or advise if anyone has ever swapped bonded pairs around before. Some background:
I have four rabbits, two males and two females. Penny, Roo, Piglet, and Pandi. The pairs are related to each other. I started off with one female(Pandi) and what I thought was another female(Penny), turned out to be male. And I ended up with two babies one male(Roo) and female(Piglet). Currently the mother(Pandi) and son(Roo) are a bonded pair housed in a large pen together. Then the father(Penny) and daughter(Piglet) are bonded and housed in a separate large pen together. Lately my husband and I have been having an issue with the Mother and Son pair. The Mother, Pandi is very dominant and is causing the Son, Roo who is normally very friendly, to become more withdrawn. If we give Roo any attention his Pandi will start biting Roo or us. So now Roo becomes fearful when we try and spend time with him. So my thoughts are to switch the Roo to be paired up with his sister, Piglet, and to pair the mother, Pandi, with the father, Penny. Piglet is far less dominant than the Pandi and she has a calmer personality much like Roo. Also the father, Penny, isn't very comfortable with us and doesn't enjoy as much attention as Roo, which would hopefully cause the Pandi to become less aggressive and jealous.
The pairs do not get along together. There have been fights previously when they accidentally came in contact through the bars of their cages, however, there have not been any fights for over a year. My fear is that if we tried to swap the pairs one pair would become bonded or the other wouldn't. Or if neither became bonded but they reject their previous pen mate out of fear. I just don't want to end up with 4 separate cages. Has anyone ever had luck swapping pairs with the car ride method?

Are all of these rabbits fixed? That is often a critical factor in bonding.

I would not advise breaking a bonded pair. You could very well end up with 4 separate cages and some very stressed rabbits.

The stress-bonding method of car rides is advocated by many however I am of the opinion that this method is only successful with rabbits that were already inclined to bond anyway. Those who have used it on other rabbits often experience just temporary success. But if the rabbits aren't inclined to bond, then the stress-bond only gives a temporary, false sense of a bond. Their disinclination to bond soon becomes apparent.

If Roo is neutered and Pandi is being aggressive toward him, then perhaps they would do better separate. If he isn't neutered (or she isn't spayed), that may be causing Pandi her issues. I personally wouldn't risk breaking up Penny and piglet.

Yes that is very important. They are all spayed and neutered.