Actually, the Roman Catholic Church holds that the saints do indeed help those on earth. Saints that are canonized, for instance, are generally those who offer proof of being in Heaven by performing at least two miracles after their death. These miracles usually take the form of healing the sick on earth.
Catholics teach that the Church remains one body that continues to cooperate together as the Church Militant (those on earth) and the Church Triumphant or Glorified (those in Heaven). The Church Triumphant actively assists the Church Militant according to Catholic eschatology.
"Canonized" saints are those added to the official liturgy of the Mass, either to the listing of the saints asked to pray for the Church at the Easter Vigil or on the day of their "victory" (death). This official "listing" is what the word "canonized" means, like the official listing of the books of the Bible. Unless the saint was proven to be approved by God before or at the time of death (usually by dying as a faithful martyr), the saint must prove from Heaven that they are still working in union with the Church Militant. Those that do prove this get added to this prayer listing or canon.
The 144,000 teaching of JWs, on the other hand, neither entails a canonization (as Witnesses don't believe you can personally ask for a saint's help by praying to them and therefore has no listing in liturgy to add their name to, i.e., "St. Joan of Arc, pray for us.") Not only do Witnesses deny that miracles can happen anymore ( thus no way to prove from Heaven that someone is there), they believe prayer is an act of worship that can only rightfully be offered to God. (Prayer is actually only a request, and not exclusively an act of worship.)
So not only can we ever know if the claimant JW partaker can rightfully make such a claim to be chosen, there is no theological belief in Watchtowerism that God will (or even desires to or can) offer supernatural validation of these partaker claim.