Add-on pay is similar to Add-on Card in the banking system. It is a privilege offered to the spouse, parents or children of a primary holder of Alipay Wallet, a mobile payment app launched by Alipay, China’s largest online payments provider. The primary payer can set the fee limit for an add-on account, within this limit, all expenses incurred on an add-on account are billed to the primary account.
亲密付(add-on pay)类似于银行里的附属卡，是支付宝钱包为主账户持有者的配偶、父母或子女提供的一种专享功能。主账户持有者可以为亲密付账号设定限额，亲密付账号发生的限额内消费账单都由主账户来支付。支付宝是中国的在线支付服务供应商，支付宝钱包是其移动支付程序。
For example:
My dad pays for everything I bought online because he applied an add-on account for me on Alipay Wallet.
我网购的所有东西都由我爸买单，因为他给我在支付宝钱包里开通了一个亲密付账号。