Hi Everyone,
we have a integration environment Between DataStage and Salesforce .Currently we are  using data loader script (process xml) file with the reference to mapping file for "upsert operation ".my requirement is to establish a relationship between Bond (at parent object) to a Coverages(child object ) ..There is a Bond field on child object defined as  "Lookup(Bond)"..In mapping file,for updating LOOKUP (I.e.Bond)  field on child object (i.e Coverage)..I have defined as below 

Bond__r_ExternalID__c=Bond__r\:ExternalID__c

With the above mapping "Bond"field (CHILD object field )is getting updated with ExternalID of Bond record (Parent externalID)
Example :Initially Parent Object "Bond" is created with ExternalID =1234 .After that Child object "Coverages" lookup field "Bond" is updated with value Bond_ExternalID=1234" .So this way coverages are linked to the Bond (Parent object).
For the same scenario mentioned :
We would like to use "salesforce pack for datastage " .How can I define a mapping for child object (Coverages) so that (Bond) Lookup field for upsert operation is updated with Parent Bond record (Parent externalID)?

Please let me know the resolution how can I achieve above requirement to work it properly.

Thanks,
Dev