First of all, it is essential to have a special pet box in use. This prop can make your third pet enter the state of "pet box in use" to avoid being attacked by other players and causing the pet to be knocked down. This pet box can be obtained through activities such as buying or challenging tasks.
Secondly, in Adventure Island, only two pets can be brought at a time. When the first pet is in the pet box, the second pet will automatically follow the character. At this time, you can use the pet command to take the second pet back to your backpack so that the third pet can use it.
It should be noted that when we complete certain tasks or activities, sometimes we have some special pets to carry, and these pets will not be included in the limit of the number of pets, so we can carry three pets with these pets.
Generally speaking, Adventure Island International Edition needs some extra configuration to carry three pets, but as long as you follow the above method, you can easily have three pets.