For reasons I'm not aware of, this evening my daughter was asking the question, "Where was I before I was born?" which quickly became "Where was I before I was concieved?". As Christians we said that she existed in the mind of God, but aside from that that she had no "further existence" until conception. This she found a rather distressing thought. Talking it through, this all became more rather than less confusing, at least initially. Many people express anxiety about the possibility of going out of existence, but here our daughter was seemingly equally anxious about at some point not having existed.
After discussions of pre-existence and reincarnation, we went on to talk about the concept of existence, about it not being a "predicate" (although we didn't use those words), and about the impossibility of imagining one's own funeral except from the vantage point of another pair of eyes. I thought the first part was essential as she seemed to think of "non-existence" as a state of being in utter darkness unable to sense or interact with anything outside herself. For her part, she seemed to find the discussion of funerals more helpful, especially once she realised that we agreed that we couldn't fully imagine our own non-existence ... but that we didn't think that meant it couldn't be (or have been).
How would you have approached this?