I'm so sorry to hear about your sweet girl, Niki. Losing a pet is hard. You know that Niki is probably wagging her tail, knowing that you had to replace her with two doggies (that's a lot of love). You were right to listen to your heart and to adopt those two puppy bears. They will bring a lot of joy into your life.
I've often thought about getting one of those kid trailers for my bike and taking my goldens w/me occasionally. One at a time, though. They are big gals (Agnes is a 96lber; Maeve, 85 lbs; and Maud, 60 lbs).