Hi,
yes this is possible:
you need to create following fields:
child_name1, child_age1, child_toy1, child_name2, child_age2, child_toy2, child_name3, child_age3, child_toy3, child_name4, child_age4, child_toy4, child_name5, child_age5, child_toy5

Now you can add following options in your Dropdown field:

1|1

2|2

3|3

4|4

5|5

and following conditions:
1) if equal to custom value 100 then hide fields child_name1, child_age1, child_toy1, child_name2, child_age2.... (Inverse No)
This condition is never met, so it always hide all fields.
2) if greater than custom value 0 then show fields child_name1, child_age1, child_toy1 (Inverse No)
3) if greater than custom value 1 then show fields child_name2, child_age2, child_toy2 (Inverse No)
4) if greater than custom value 2 then show fields child_name3, child_age3, child_toy3 (Inverse No)
5) if greater than custom value 3 then show fields child_name4, child_age4, child_toy4 (Inverse No)
6) if greater than custom value 4 then show fields child_name5, child_age5, child_toy5 (Inverse No)

So for example if I choose "3" then:
- condition 1 then hide all child fields
- condition 2 then show child_name1, child_age1, child_toy1 fields
- condition 3 then show child_name2, child_age2, child_toy2 fields
- condition 4 then show child_name3, child_age3, child_toy3 fields