What role will those godparents, or rather what role are they permitted to maintain in their lives? They are close friends of ours, and good, faithful people.
I suggest they maintain the roles of close friends of yours, and, faithful people.
They bore witness to your children's baptism, rebuked Satan on their behalf and professed belief in the 'One holy, catholic and apostolic church' for them at that time. Now you are completing your children's reception into that one Church, the Orthodox Church, through reception and Chrismation. If your close friends are good and faithful people as you say, they will understand the choices that your family has made. Keep them in yours lives, talk to them about your decision and renew your love for them. OZGeorge's advice in spot on.
