What could these 2 girls be missing?

In my opinion it is a deficency in phosporus. Those plants are using the stuff from the leafs, and this process cant be undone. I think those yellow leafs will be dead in a few days. This is a natural process from the plant.

Looks like a nitrogen defiency to me. No saving the older leaves but I would add some earth worm poop to the soil and give it watering. In flowering you would need as much nitrogen so a slow release worm poop may help. Good luck and add some worm poop to your medium every grow.

See how the smaller lower foliage is greener than the upper foliage? If it was just a nitrogen issue it would be the other way around, so it's not nitrogen to my eyes. Nitrogen and magnesium are responsible for the "Green" of the plant. Chlorophyll production. But, a Lack of Sulphur can also cause a general paleness and yellowing uniformly across the plant. If you are using a bottled nutrient line, they are generally formulated towards the production of cannabis. Grandma uses a miracle grow hand held spray pump fertilizer to feed her house plant. Dope growers use bottled lines. So if thats the scenario then i doubt you are lacking any elements. The next thing i would check is the pH of the soil, and the next thing after that i would test my solution's EC to see how much they are getting. If your pH, and EC are acceptable, then You might have a lockout due to salty soil. In which case you will need to flush out those salts from around the roots so they can take up water more easily, and my extension, nutrition. Over feeding of salt based nutrients isn't a good idea. It fills the media with salts and can create more problems than it solves. And based off you saying you over fed twice, it's more clear that it's a potential lock out situation due to too much of 1 or more elements. If you determine that a flush is necessary, then use room temperature water. Room temperature water will aid in dissolving salts better than cold water. Some won't dissolve at all if the water is cold, so do room temperature water. And pH your water as well because this is a good opportunity to correct any pH shortcomings. 6.2 in coco coir. Make sure there is a lot of runoff out the bottom of your pots. If you have a 3 gallon fabric pot, then run 3 gallons of tap water pH to 6.2 through it so a lot runs out the bottom. If you can find a product called Yucca, it's been shown to be very good to add to your flush water, as it does something to water molecules that forces them apart. And what thats supposed to do, is ensure that dead or dry spots that the water doesn't flush through, will get into those dry pockets so you know your entire root system and soil volume has been flushed 100% It's not necessary to use Yucca. I'm just telling you what it does and the benefits of using it. I don't personally use it, but you have asked questions so it's important to me to give you as much advice and options as i can for my own satisfaction After you have finished the flush, return the plants to the grow chamber and leave them be. Let the soil dry out so the pots feel light, then resume feeding. And make sure you pH your nutrient solution to 6.2 before you water in.

lock out

They are missing tooooooooooooo many leaves for a start and suffering from a potassium deficiency. Remember......less leaves = less energy being made = less potential growth! Add a P/K booster to your feeding schedule, or up the dosage if already using one. Remember too.........what is showing now in the leaves is a direct reflection of what was occurring in the root zone 2 weeks ago.

Seems like a potassium deficiency coupled with lockout and nutrient burn. Perhaps too much nitrogen in early flower. Dropping leaves suggest not allowing root zone to dry enough, space out giving her water for longer intervals. Should be fine

Check your pH . Sounds like you are feeding enough but it won't use the nutrients efficiently if the soil pH is off. You can take a run off reading to give you a rough idea of where it's at. Also tak an EC reading. Nutrient lockouts are usually caused by improper ph or excessive feeding.

Looks starving… But I can't tell without a linked diary.