Battery chargers contain circuitry to limit the charge current and voltage. If you just hook them up to a power supply directly, there's a good change you will cause a fire.

Also, when you connect the batteries all together, they will probably be at different voltages. The higher voltage batteries will immediately dump a VERY large current into the lower voltage batteries. The result will also probably be fire.

You need each battery to be charged independently by their own charge circuit. You can power all of the chargers from the same power supply though, assuming it has enough amps.

The TP5100 would be a good charge controller for this use case. You will need to remove one of the R100 resistors to reduce the current to 1 Amp (2 Amps is probably too much for most HT batteries), and solder the "SET" bridge to set it for a two-cell battery (most HT batteries are 2S aka 7.4V). You could change to a single R200 if you'd like to reduce the charge rate to 0.5 Amps. I think Baofengs charge at 0.7A normally, for example.

So if you were to do 4 chargers, each at 1 Amp, you would want a 10-12V power supply capable of 4 Amps output.