In this fast-paced modern day world, most people have a bad tendency to forget what is called "Manners." In the Native World of Elders & People, it is always very wise to remember you just DO NOT walk up especially on two people in conversation and just butt right in!
Usually Elders or others, that are talking in private, they are usually teaching in some compassing or maybe sharing a personal "Spiritual Experience" that if interrupted could have been a great help to that other person. Always remember how you would feel if someone just butted in on something of importance to your learning and sharing. It is a two-way street either way!
The Proper and Respectful Way is to stand back out of earshot, (To Give Them Privacy) and wait till you are invited to come closer. An Native Elder or Native Person will usually give you a nod of his/her head or look at you, to acknowledge that they do see you are there waiting to speak to them. Then when they are ready for you to join, one or both will motion for you to join them. Until then learn another lesson here...called patience.