Check out page 12 of Tome & Blood. (in the familiar section, under Death of a Master)
If a master dies part of the master lives on in the familiar. It loses extra Hp's & skills it gained from the master but retains most of it's familiar abilities. it is treated as having a master 2 lvl's lower (but never below 1st) if the master is brought back, the bond is reestablished, & the familiar is as per a familiar of the masters lvl should be.
That's kind of a condenced vers. of what's in T&B.
I don't know if this is what you're looking for or if it aplies?