So sorry to read of your loss, Llama, how shocking for you all!
I'm glad that your sister is with you and is helping you with phonecalls, and agree that it would be a very good idea to just call a couple of friends and ask them to tell others, and to field return calls as well.
There is a "concentric ring" model, with you and your DD (and PILs) at the centre as being the most affected - you should be able to rely on people in the next ring out, and they in turn need to gain help and support from another ring out, not from you. So all the support is going inwards (I'm not explaining it well, I'm sorry) but no one is expecting anything of you that you are not able to give.
Take all offers of help now that you can bear - and contact people who ask you to let them know if you need anything. Even if it's just "could you please come and help me with housework today, I just can't bear it".
I see peachgreen has already seen and posted on the thread, and offered up Widowed and Young, and Winston's Wish - very useful organisations, please contact them when you are ready.
for you - so sorry you are going through this. x