Stress Stripes?

[SolomonFinch]

2 of the female in my tank were very, very aggressive within minutes of entry. One developed stress stripes and just CHASED her five sisters, biting away. She was spastic! I removed her and put her back into a 1 gallon before she hurt her more peaceful sisters or had a heart attack.
The 2nd girl was aggressive as well. I removed her.
I dont know how long it should take a betta to acclimate to her sorority, so I didn;t want anyone hurt.
My question.
This 2nd fish has stripes. 24/7. her fins are also speckled (natural color, not fin rot) She also has a tiny dot at the end of her body, on both sides, a black set that matches her specked fins. Odd thing, her fail fin is red, matching none of the rest of her coloring. She looks like a speckled trout. She had these when I received her. They have never darkened, went away, faded, and are not associated with any circumstace.
Now, I realize my first girl has a tendency to demonstrate stress striping....but my 2nd girl....is she just a striped fish? I have never seen a striped betta. they run the legnth of her body, so is not like the ones indicating she is in heat.
2nd question....are these 2 gals doomed to live alone in separate tanks from their sisters? Like I said, within 5 minutes they demonstrated so much agitation and the one even SOUGHT out the others hiding from her to bite them, I feared for everyone's safety.
If so, I guess I am off to buy 2 more permanent set ups.
I have a so far going well 5 betta female tank going...

[SolomonFinch]

I realize i should have added all 7 at once....but the other 2 required quarantine for possible disease as I didn't want to infect the other 5 who passed my little health test. I kept them in quarantine BESIDE their sisters tank, in hopes that would acclimate them to the scenery and their "sisters". I had hoped to add color to my tank, as I have 2 peaches, 3 whites.
Can additional bettas EVER be added to a sorority after the initial set up?
Sorry for so many questions. You guys are always so nice and knowledgeable.
I would like to add that I have a single male betta that is my <3 and started this whole business, my husband has 2 males and I also have one fancy goldfish aquarium and one shubunkin tank, all successful tanks Thank God.
My fishies are my babies and company and I find fish keeping to be more relaxing than anything. My aquariums bring me so much peace and joy. I only want the best for them. I am just so new to this female betta stuff. The "boys" and goldfish are so easy!

[babystarz]

The best way to add additional females to a sorority is to remove all the fish, re-arrange all the decor, then add the girls all at once. This way any previously established territories don't exist to defend, and the girls will have to refigure their pecking order. Some stress and nipping in the initial 48 hours is normal. And of course some fish are just too dominant or submissive to be able to happily live in a sorority, so there's a possibility you'll have to remove the shy one anyway. But give it a few days.

[SolomonFinch]

Thank you. :)
That is very good advice I actually would never have considered.
I plan to do this with the fish that seems to have mellowed a bit more.
I am pretty sure "The Shark" is being adopted by my teen daughter, LOL She just isn't a social gal. (The fish, not my daughter, LOL)