>Edward also made it clear to me that I am didn't describe that aspect clear enough. Rreading my text, I understand that.
>
>The resulting table should be a concatenation of the 4 tables, with all duplicates removed, but that should happen in an evenly distributed way, like the numerical examples displayed.
>

Lennert,

If you wish all duplicates removed, then it is called distinct records. If you wish duplicates NOT INCLUDED, then it is called unique records.

Cannot see and cannot understand what the "proportion" is here for.

To get distinct records (where there are all unique records, and only one if duplicates found) then you can use UNION.

sele DIST * from table1;
UNION;
sele DIST * from table2;
......

To get unique records only you may use something like:

sele * from table1;
UNION ALL;
sele  * from table2;
UNION ALL;
......
into cursor tempcrs

SELE * from cursor group by field1,field2, field3,...., field_last HAVING count(*)=1