dd understands as she has had freinds die.
today I told her about her nan. I got as far as "you know nan has been very ill" and she looked at the ceiling(heaven) no tears, but she understood.
I asked her later, just to check she understood, "where is Nan" she looked at the ceiling again and sais her dads name(she calls him by his name as she can say it easier than dad) and I said "what with dad's dad"(who is dead) and she said yes.
I was gobsmacked.