With the examples on page 105 of sense sharing and mental communication the effect has to be instilled in the bond twice one time to put thoughts in the mind of the familiar and once to put thoughts in the mind of the magus. Wouldn't this be similar?
from page 105 "powers are limited to effects which target the maga, the familiar, or both." I think the intent of that statement is that you can't have a power that targets one of them or one that targets the pair of them together but you can not have a power that targets either one individually depending upon which one needs the power.