Grid like footprint on kicad for RPM5-3 component
That is a distinction that you make in the symbol rather than the footprint.

In the symbol editor, you can "stack" pins on top of one another, so that they all connect.  I'd stick with the datasheet's naming convention (A1, B1, etc).  When you create the stacked pins, make one of them the actual pin type and all of the others "passive" and invisible like this



Then, move the pins so that they all overlap like this



In your schematic, you won't see the grey pins (they are invisible) unless you specifically request them.  Then your netlist will connect the pins together for pcbnew.