Steve has been on the staff for 5 years now, 4 years as Coaching Assistant and 1 year as Safeties Coach. I think Bill set the standard with Steve on how he'll treat his son and by all respects he was, if anything, extra harsh on Steve and Steve had to work twice as much as others to prove himself and get promoted. Infact Steve's talked about that. All the secondary has huge respect for Steve.
So the precedent has been set with Steve and hence adding Brian shouldn't be an issue. He'll be Coaching Assistant for a while and will have to work pretty hard to prove himself. The Pats keep a small staff and everyone has to work very hard.