The Double Delux package includes absolutely everything you need as well as a few spoils. The Maxi-Cosi FamilyFix base which is used from birth with the infant seats installs safely and securely with isofix. The Maxi-Cosi Pearl will install onto the base from 1 year with till approximately 4 years in a forward facing direction. You will therefore have one base from brith to 4 years. Should you prefer to keep your babies rearward facing then please visit the packages which include isize bases and car seats. Install two carry cots onto the frame so that your babies can lay flat on those long strolls.