https://amzn.to/2MerbIPClip coupon then add 3 to cart
I am not Amazon Family (shared Prime) and got it to work
Promos of 2 and 3 are stacking
Order Summary
Items (3): $149.97
Shipping & handling: $0.00
Echo Dot 2 Pack: -$40.00
Amazon Family Promo: -$15.00
Echo Dot 3-pack: -$40.00
Total before tax: $54.97