Kavod ha-rov! I am the only cohen in our kehillo chutz la-oretz. There is also a levi, but the gentleman is very old so he cannot wash my hands before duchening. Therefore our practice was that a first born son washed my hands. A rov that visited our shul said that we should abolish this practice and therefore I was unable to duchen on shavuos this year. Could you please give me a psak din about whether we should continue with our practice or whether there is any other halachic way for me to duchen with properly washing my hands. Thank you very much.

In such a case it seems that the First born may wash your hands. Though for those who paskin like the Kaf HaChayim and the Zohar HaKadosh - both prefer for the Kohen to wash his own hands in a case where the only other option is a First born. Obviously the First born needs to be First born of the mother and not the father. Rabbi Baruch Kitay