You could create an SQL query component, which looks up the affected users Manager, then use that during the incident creation workflow. If the affected user has the specific mananger you are want give access, then have the process add him as an additional contact.
Now for 7.5 you would created a seperate workflow (since you no longer can modify the core workflows) and called that work flow during the uponticketcreation ruleset.
Hope this gives you some idea where to go from here.