It's possible, on a joined query, to update fields from both tables?

Let's suppose following TIB_Query:

SELECT A.FIELD1, A.FIELD2, A.FIELD3, B.THEOTHER
FROM A
JOIN B ON B.ID=A.FIELD1
FOR UPDATE

FIELD1 is the primary key for table A;
and the EditSQL:

UPDATE A SET
FIELD3=:FIELD3
WHERE FIELD1=:OLD_FIELD1

This works properly for update only one field.
But, what about updating B.THEOTHER? How?

Thank in advance,
Hugo.