I think I got what you are looking for. This requires your table to have a unique record id [PK]. This is represented by KEYID in my SQL. I have also used CUSTID instead of ID in my SQL.

select custid, keyid from patients where between(age, 0, 18) group by custid into cursor crsUniqueChildren
select custid, keyid from patients where age > 18 group by custid into cursor crsUniqueAdults

select insurance, count(*) kount from patients where keyid in (select keyid from crsUniqueChildren) ;
   group by insurance ;
   into cursor crsChild
select insurance, count(*) kount from patients where keyid in (select keyid from crsUniqueAdults) ;
   group by insurance ;
   into cursor crsAdult
select *, 'C' Age from crsChild ;
   union ;
select *, 'A' Age from crsAdult ;
   order by 1 ;
   into cursor crsKounts