You can own an unlimited amount of pets, who will remain safely in your nursery until you select them as your active pet. You can browse your nursery/unwrapped pets using t!pet nursery.
Switching your active pet
You can change the pet displayed in your house and that you can interact with. Any pet in your nursery can be selected to be your active pet.
At any time, you can use the command t!pet edit> 1 (Active pet) > 1 (Retrieve/replace active tatsugotchi) and navigate the menu to select the pet you would like to select as your active pet. If you already have an active pet, you will need to pay a fee of 2000 credits to send your current pet to nursery for safe keeping. Pets in the nursery will stay there until you take them out.
Sending your pet to nursery
If you would like to send your active pet to the nursery for safe keeping so it does not run away while you cannot interact with it, you can use the command t!pet edit pet > 2 (send active pet to nursery). This action will cost 2000 credits, but your pet will stay in the nursery until you choose to take it out using the above guide.
Nursery pets in Daycare
Pets in your nursery can be displayed in your daycare for cosmetics purposes and to send them on fieldtrips for some passive XP gain. Pets in your daycare cannot be selected to be your active pet, so you will need to remove the pet from the daycare before selecting it as your active pet.
You can use the command t!dc edit storey > Select the storey, if you have more than one > 2 (Daycare pets) > Add or remove pet
Once in your daycare, you can send pets on fieldtrips using t!fieldtrip send. This costs 500 credits per pet. Your pet will take 20 hours to return, at which point you can use
t!fieldtrip claim to retrieve them, you will receive any items they found and each pet will be awarded 400-600 XP. You can view t!fieldtrip chartfor more details.