Hmm... Your mention of "1 4 18" made me realize I didn't even consider the factor of "1" as possible, which makes a number of more age groups possible. Namely: 1 4 18 = 23; 1 2 36 = 39; 1 3 24 = 28; 1 6 12 = 19; and 1 8 9 = 18 (and I guess, since it's the daughters' father, and the mother might be different, 1 1 72 is also a possiblity). But it looks all these sums are all singular, so it doesn't break the solution I came up with.