You can store this in the fridge until ready to serve.
At service you can serve each guest individually, filling glass with ice, then fill 2/3 full with punch base, topping off with seltzer water and a splash of grenadine.
Or you can mix punch base together with grenadine and seltzer water and add ice and punch to punch bowl to serve.
Notes
You can find mango nectar in the bottled juice aisle at the store. You can find Coco Real, sweetened lime juice, and grenadine in the liquor aisle next to the mixers.
If you want to make this a party punch for adults, I've heard a shot or two of Malibu Rum in in each glass before pouring in the punch. It makes this tropical party punch extra delicious!
This recipe can easily be doubled or tripled for larger groups.