Robin 3 came at a similar time to robin 2, it was sometimes very difficult to know which one was there, but they both came and fed from both our hands! It seemed that they shared the time and the mealworms. Yet they had very different characters and ways. One like to land on ornaments and garden items before coming for the worms, the other one always flew straight from the bird feeder, right across the garden and straight onto the hand.
I managed to get a few videos of robin 3 (and 2) but still can't work out which was which at times!
They could have been a pair, there was never any chasing off, it was one or the other...
again both fed from our hands!
Once again, we never trained any of these robins, they just seemed to know they could trust us and flew onto our hands, even with food in other places. When there are other larger birds in the garden it is easier for the robins to collect from the hand where no other birds are going! - although we do put robin food in a quiet are of the garden away from busier areas.