The Play Kit recommendation is based on your child's birth date and when he or she will grow into the next development stage. Each Play Kit is therefore tailored to the age and development stage of your child. If you would like both of your children to have the Play Kit subscription, we suggest you sign up for two subscriptions, each for the specific ages of your children. You could then cancel one of the subscriptions as soon as your younger child reaches the age of your older child, at the start date of the subscription.