Too much Nitrogen at one time can burn them and too little will starve them. Also the Nitrogen needs to be cut back but not eliminated during flowering as too much Nitrogen can inhibit flowering. The key to nitrogen is that it is a building block for green plant growth but it is acidic(which is why it tends to burn the plants if too much is given). When the plants get started, they aren't able to handle as much but once they get growing vigorously then they want a lot of it, along with other minerals, water, and light energy.
Once it is time for switching over to flowering(in nature) it will have used up much of the surrounding nitrogen and will start using other available nutrients for flowering(phospherous and potassium, and trace minerals) If there is a lot of nitrogen still present then it tends to block the flowering hormones.
On the opposite side of that
is where you may be. That is that the plants are in limited amount of soil and nutrients(even though you are feeding with supplimental nutrients). Early on the plants have access to hot soil and will grow like mad, steadily eating up the nutrients in the limited soil and thinking that they will be able to grow big. Then when they have chased their roots all through the soil and eaten up the nutes, they hit a wall and stop growing so fast.
At this point they have become root-bound and when you feed them, you are either not giving enough or the soil isn't able to hold the amount that the plant is needing and it falls short. At this point the plant starts to rob the nutrients that it needs from the lower leaves(that in nature would be shaded and useless anyway) to feed the most important part, the buds.
For you now the problem becomes what to do for the plants that are flowering. And that depends on how far they are into flower. If you only have a few more weeks then its too late to do much. You could add a few light doses of micro for the next few feedings to keep them going. You most likely will not see improvement with that but no worsening either.
The girls in veg are different though. I would suggest getting them into bigger containers of soil so that they have room to reach out for new nutrients and continue to feed them. I don't know the setup of those nutes and being in soil as I am a hydro guy. However the agenda is the same, and that is to give them just enough nitrogen to carry them into flower but not too much so that it can fall off gradually to a point halfway into flower that they are nearly out of nitrogen except for the little bit that you give them. This way they will start pulling nutes from the fan leaves toward the last 2-3weeks of the life cycle.
All that said, you probably can't do much to improve the flowering plants other than to give them some micro shots and make sure the water's PH stays around 7.0 going in. This should carry them to finish.
But you need to find the balance of nutrients in the soil and what you give them and the length of time that you grow them. Having them for several months will require either considerable feeding or sizable soil containers. Good luck with it