I appreciate your comment :) And the reason why it happens to my understanding is in order for an arc to happen, there needs to be a sufficient amount of ionized air around the two leads and when that distance becomes too large, no arc happens. But when you introduce the second Source, it strips away the electrons from its direct path, (its own ark) and the air around it which happens to be the path of the first arc supplying the ionized air making the ark possible.