Telling a grown up child you are pregnant again, now that's something I'm never going to face because I'll be way past childbering age before my sons' are adults. Can imagine it's not the easiest news to break, though.
Who tells the news you're pregnant? I must admit this is something I feel strongly about. Once we'd decided to go public, I got irrationally upset if my dh told family and mutual friends that I was pregnant. I remember seething in the background while I heard my dh telling on of my close friends I was 8 weeks pregnant.
I knew the news would result in questions about my morning sickness and what sex we hoped for, etc. As soon as people know you are pregnant, IME all sorts of things become public property. My body, my news. I also like to see the reaction on people's faces when you tell them. You can learn a lot from that first reaction.
As for when, in the first trimester we agreed to tell on a 'need to know' basis, as well as close family. I preferred to tell few people, though would have revealed all on mumsnet.
The very first time I was pregnant, age 34, I had a miscarriage at 10 weeks. We told lots of people I was pregnant and the news was greeted with great surprise - most people had assumed I didn't want children. Therefore news spread fast. I was still coming to terms with the idea of motherhood (and quietly panicing) when I lost the baby. I then had mixed feelings about the miscarriage, especially since it was an early one. I felt very confused and this was not helped by the fact that total strangers, people who knew my husband or a friend of mine, came up to tell me how sorry they were I had lost my baby. I felt like a rabbit frozen in front of a car's headlights. Didn't know what to say or do.
So, Duffy if you want advice, I'd say tell few people till after the first trimester, and if poss, tell them youself.