How do I add a second name to an address listing?

In Yahoo address book - you can add a second telephone number. Or a second address. Why is it no longer possible to add a second NAME? As an example, my son has an email account. My granddaughter does NOT have an email account. I'd like to be able to list my granddaughter's name in the same address record as my son (she's six and does not write - let alone email).