Har Nof eruv

Question

We have friends coming to visit us in Har nof from the US. They are sefardi and their Rav does not rely on a city eruv so they don't want to go anywhere on shabbos because they have a baby. I know some improvements were made to the Har Nof eruv and it is better than a standard eruv. Are they allowed to use it? What specifics could they tell their rav about the Har Nof eruv that might allow them to use it? Thanks.