Greetings Peter,
Do you mean other WCAs as in another WCA Type or Usage ? Either way, you will need to select entries from the WCALA table and select on the appropriate WAPITYP or WAPIUSE field value respectively.
The WCAs should be linked to each other via a Work Approval if you are using the Enhanced model.
Therefore, the logic has to be:
Select the Object number for the WCA#1 as described above
From WCALA, select FATHEROBJ where CHILDOBJ=your WCA#1 object number and CHILDART="WA", FATHERART="WW".
Then select from WCALA where FATHEROBJ=the Object for Work Approval,
CHILDART="WA", FATHERART="WW",
and CHILDOBJ<>your WCA#1 object number
Join with WCAAP as above to select the appropriate WAPINR, WAPITYP or WAPIUSE if needed
