In a word, no.
there is only one tenet that a JW must believe - that the governing body IS the faithful and discreet slave, the representatives of God on earth.
As you so correctly pointed out, if they don't know who THEY ARE can one be sure they know who you are? As for older ones there may be some room for them to not keep up with the chariot and believe that all the anointed 144,000 are the FDS but that's all the leeway a JW might get. To believe that ALL Christians are Christs brothers,saved , anointed with Holy Spirit or however you wish to put it - well, that would simply get you disfellowshipped if you spoke out which a Christian must do as Christ commanded to preach the good news.
sorry if this is going to be hard on you, were you perhaps thinking of joining for those you love???