I recommend jarring them somehow anyways. IF there is a chance something is floating around you would have a better chance keeping them individually. Go out and buy a few jars, dollar tubs, anything. Even kitchen stuff would work for now (rinsed very very well). Trust me it is in your best interest to make sure your fish survive.
Adding the bottom feeders all at once could cause the tank to have higher ammonia, therefore now going through a new cycle. HOWEVER if you have 0.25 ammonia, the bettas have come in cups with up to 5.00 ammonia and survive miraculously. I don't know if the bottom feeders are even more hardy than that, but I still recommend jarring the bettas.
Then you have to re-cycle your tank. Since the meds and new additions have come in, the cycle basically no longer exists. Which is why I use meds sparingly and always ALWAYS quarantine... healthy looking or not! Never add more than 2-3 fish (depending on tank size, for your tank it's fine) at a time otherwise you risk an ammonia spike.
If you can get the bettas jarred somehow, you can float them in the tank to keep the temperature up. Use tape or something to hold them still so they do not float away. Clean the water every day, adding water of the same temperature.
Has anything in the tank changed other than new arrivals? New conditioner? New food? New heater? New gravel?