As tiny babies, that would be an excellent idea. Putting them together.
You will need a brooder.
The least money way is a chicken heat lamp and light and some kind of thermometer to not cook your chickens. Remember: the heat will be HOT down inside those plastic bins. So you will want to give them a cooler area to run to if needed.
You will need to clip that kind of lamp higher above the plastic bins to get the heat right.
This is also a good time to get your coop and outside run built. You will need it as soon as its built. Because the babies can go into it.
But, its dangerous to use the heat lamp in a coop re: Fire

Hazard