First off, I'd say to get those fish out of there if you have the option to do so. If you have an older established tank, think about transferring them in order to save their lives. Setting up another tank wont do any good because it will have to cycle as well. Your cycle process has already started since you have fish in the tank so you can't do anything to speed it up really. Add some gravel or decor or something from an older established tank to help get things going, but I doubt that will help for what is to come.
I can't speak for the chemical additive; I've not tried it, although I haven't read anything good about it either. At any rate, I'd have to say that even if it did lower the ammonia concentration you have a long ways to go and many more things to worry about. Once your Ammonia levels drop your tank will experience a rise in Nitrites that will far exceed the length in time that your ammonia spiked. That period was the hardest for my fish. Even daily water changes wouldn't bring the levels below the critical mark and only prolonged the cycle time. At this point I would say all you can do is hold your breath and see what happens. Of course do whatever you can to keep the fish alive, but just know that everything you do will have consequences. Chemical additives will more than likely NOT work at this point and may only cause undue harm to the fish. Water changes may dillute levels SOMEWHAT however, this will also increase the time it takes to complete the cycle process. I was on top of my tank and knew the water parameters as if my own life depended on it when I first set it up. As hard as I tried, I could not save all of the fish. I only lost a couple but I don't doubt that the rest suffered. I've learned a lot since then and I know I won't make the mistake, again, of putting fish in a tank before its completed it's cycle.
Remember, the more fish you have in there, the larger the bio-load on the tank. This means that its going to take even more bacteria to handle the waste. This increases the cycle time dramatically. Hopefully your babies dont create that much waste but they grow FAST!! Your tank is going to have to catch up with the load and grow with it fast. You may be in for a long, long cycle time. Hopefully your fish will survive.
One thing you should probably think abouit doing in the near future is getting a larger tank, or in the very least, a few more smaller ones. Just get them cycling before you put fish in them. When your babies grow up, they are going to be a huge load on a 6 gallon tank....I dont really think it matter what kind of fish they are!
Best of luck and let us know what happens! There are sooooo many people here with great advice. So far they dont even seem to mind answering the same questions over and over( and over, and over
) Truly, these people are great help. WElcome and good luck!
