You've confused me a bit here. On my routes, two people can buy 40kg then increases are in 3kg lots. For your weight you would buy 43kg, not 60kg (or 61kg to follow the 3 kg increases).

If you've purchased 3 bags between 2 people plus increased weight, then the split you describe is OK, but Easyjet ground staff might not know this so take screenshots or something in case.