Is this what you're asking for?

Cursor 1 & 2:

for select Field1,Field2,Field3
from Table1
left join Table2 ...
where Cond1 ...
UNION
select Field1,Field2,Field3
from Table1
left join Table3 ...
where Cond2 ...
into :C1,:C2,:C3
do

I haven't actually done a union in a 'for select', but assume this is how
it is done.

HTH,
Set