Celine:
Lowest: probably Unison with maybe 20 copies, idk, Soundscan didn't exist then.
Highest: A New Day Has Come, 558K
Whitney:
Lowest: her debut I'm sure, maybe 53 copies
Highest: I Look To You, 305K
Barbra:
Lowest: Who knows, most of her shit's from back in the day before #1 debuts became the thing
Highest: Higher Ground, 207K