My subscribers are usually parents and the details they provide include the names of their children as a custom field. Sometimes we send emails addressed to the children (with their parents' permission) but how can I use Liquid to include an if/else personalization depending on whether the parents have filled in 1 child's name or more? I'm trying to personalize the broadcast so that if the subscriber has two children the greeting is Dear Child1 and Child2, but if the subscriber only has one child the greeting is Dear Child1