[Maximo]

I wouldn't use the shock style collar. Some people here have had success using a spray bottle combined with commands.

Is Lily barking during the walk/outing? Are there certain triggers like dogs and people?

I sympathize because Max barks when he is excited. It helps to take him out alone periodically to train. He isn't food motivated outdoors, so treat training doesn't help. We do train indoors for basic commands and that does help. Frequent practice being around barking triggers also helps.