retrieve siblings by xpath?

is there a way to retrieve all siblings without retrieving the parent first?   so let's say we have an object called ‘fish’ from tuna, we want to find all siblings, so shark, salmon, etc…   currently, from tuna, I retrieve the parent via association, then retrieve a list from ‘fish’. this is 2 retrieves (right)?   can this be done in a single retrieve?
1 answers
[JobManagement.Jobline_Order /PurchaseOrder.Order/JobManagement.Jobline_Order = $Jobline]
[ENU_JobStatus = 'unplanned' or ENU_JobStatus = 'planned' or ENU_JobStatus = 'active']

this seems to work, so I go to the parent, then back to the child, where child = child

and added some other enum queries.


is this more efficient then going back and forth over an association?