Meal time, Growmies!
Since I discovered it yesterday with the lady, her condition has clearly worsened. The soil is slightly acidic, and I don't know what she might be lacking. Should she leave the tent to protect the others?
Doesn't look like a pest infestation to me, but more like a calcium deficiency. A calcium/magnesium supplement is a quick and direct solution. If you don't have a Ca/Mg supplement, you can try adding a teaspoon of hydrated lime to about 4 liters of water and use that as feed.
The problem, if there is one, cannot jump to the other plants. I would repot them in at least 10L pots and adjust the pH of the water you use for watering to slightly alkaline, around 6.8.
What are you feeding it?
Why have a diary and only provide half the information?
Whatever the problem, it will not jump from one plant to another.
Pots are waaay too small also.