For your sister, the Merry Widow website might be useful - it's specifically for younger widows, so she'll find lots of other people on there going through the same thing. I found it very helpful (for practical advice, plus general venting and support) in the first year or two. The founder of the website has also written a book, which is meant to be good.
For her to help the children deal with it, the best resource is probably Winston's Wish - lot's of useful advice on the website, a helpline to call, and more direct help if you're in their part of the country.
There are a few books I found helpful, but can't remember the titles - will return.
A book which helped me is Relative Grief by Clare Jenkins and Judy Merry. It's a collection of short pieces of people telling of their experiences of bereavement, their feelings, how they coped. It is written from perspectives of daughters, sons, wives, husbands,siblings, parents etc. etc.
It is not a heavy book to read and because of the way it is written it is easy to dip into.
Glenshee that is beautiful. I read it at my dad's funeral last year. I essentially read it for his grandchildren ...but also for the small child I think many of us have inside.
This is a wonderful classic: http://www.amazon.co.uk/No-Matter-What-Debi-Gliori/dp/0747563314
"Does love wear out?" said Small. "Does it break or bend? Can you fix it, stick it, does it mend?" .... Small said: "What about when we are dead and gone, will you love me then, does love go on?" Large held Small snug as they looked in the night at the moon and the stars shining bright. "Small, look at the stars, how they shine and glow, some of these stars died a long time ago. Still they shine in the evening skies, Love like the starlight never dies...."
NB: Pay attention to the edition however, there's a new hardback version where the bit about death is completely taken out
It's hard to read this book without tears in your eyes... still, these things need to be talked through and books like this help...
My DSis's DH has just died, it was quite sudden. She is left with youngish children. I don't live near her and have a young family of my own so I am limited as to what I can really do for her. She has a wonderful support network around her, I want to help but feel helpless.
Do you have any suggestions about anything I can do, other than just let her know I am here.
Are there any books that have "helped" (I know that is probably a stretch as books are so personal)? Either with her grief, or could help her with dealing with her children's grief?