vRA 7 incident update wokflow

Using EBS of vRA 7  and IaaS Blueprint to clone VM We have 2 different workflows ..one in Pre Building that inserts incident in Servicenow ..this works correct ....but the same incident never updates in the pre provisioned phase

Any pointers for update incident ?  how do we use the output  of workflow in Prebuilding  as input incident that needs to be updated in pre Provisioned phase ?

Any pointers appreciated