Using my Air Tags for Tracking my backpacking children

My 59 year old son and his wife are going backpacking for five months in Asia and I was wanting to follow their journey with my air tags with their consent of course. However, it appears that this is not something that can be done as every time one of them moves their backpack, the air tag emits a sound. Am I asking the air tags to do something that they are not allowed to do or do I need to alter my settings? My apologies if this is a lame question...my only excuse being that I am a 76 year old mother who loves and wants to maintain contact with her only child and his wife while they are away for five months. Thank you!