When circumstances are perfect, or nearly so, viable colonies can be started with very few bees (perhaps 1/4 pound or 1/2 pound) and a fecund queen. When circumstances are otherwise, it can be very difficult or highly improbable for smaller/younger colonies to grow from, "just started" to "strong and well-established", even those started by three or more pounds of bees.
When you add in factors, such as climates with cool nights, cool days and cooler nights or climates with low humidity and high temperatures; low forage availability or few foragers; high numbers of drones to worker ratio's; laying workers; poor genetics; too many honey bee predators; honey bee parasites and diseases, etc. It can be that the odds of success are certainly stacked against them. Many times it is we beekeepers who can make the difference by stacking the circumstances more towards the success of the bees. I call it "micromanagement", and not all beekeepers, it seems - especially many commercial level beekeepers, go to the trouble or expense to attempt nursing weak/damaged/underperforming colonies, in the hopes that they will recover their strength, or grow strong if they were never yet, well-established. Doing such things as reducing the size of their hive, feeding, adding brood and bees from other hives, requeening, moving to better forage areas, and many more management practices, all designed to give the bees an advantage, can be used.
I have sometimes spent an entire season, from early Spring until late Autumn nursing dinks or slackers [hives that are weak or underperforming, for whatever reason(s)], just because I wanted the practice. Sometimes my efforts were successful, sometimes not, and sometimes I believe the cost may not have been worth the learning experience garnered, but sometimes it was.
Without knowing the exact details of your dink colonies' history or personally observing its situation, a precise prescription for recovery is not possible. However, I can suggest; reducing them to a box that is only a comb or two larger than the bees can cover; give them a frame of honey for every two or three frames covered with bees (place the honey frames on the outside of the other combs); remove any frames with dead brood; leave them the combs of oldest live brood that they can easily cover. Their population is going to be falling, so you don't want them to have to deal with dead/dying brood, or more brood than their falling numbers will be able to care for, until new bees begin emerging to turn their population around. If you can obtain combs of emerging brood, to donate to them, it could be the best help possible.