wire the mains live , neutral & earth to the power supplies L,E,N terminals

if the stepper drivers have opto-isolated step & direction inputs

you only need to connect the power supplies DC output to the stepper drivers DC power in

and the breakout boards step , direction & common (which could be either 0V or +5V depending on how you wire the stepper driver input)

what stepper drivers do you have ?

on some systems you may find the negative DC output connected to earth
(like a PC's AT or ATX power supply , [common black wires internally connected to earth])

did your original power supply have the negative output linked to the mains earth ?
if it did you can do the same with the two new power supplies

John