What are Sharia rules for distributing assets of a deceased with a Will and step-children?

Assalamu alaykum, I am writing to you on a personal matter in relation to an inheritance claim. I wish to find out from you, what the Sharia guidelines are in relation to rights and responsibilities when distributing a late person’s assets. In summary this is the situation: ? My mother and father divorced when I was 2 years old. ? My father never paid any maintenance towards my upbringing. There was no connection with him whatsoever because he made no effort. ? My father then married a woman who had 4 children from her previous marriage. My father then had 3 sons with his second wife. His sons are all adults now. ? In January 2007, I discovered that my father had cancer. Despite the fact that I had no contact with him, with the blessing of Allah SWT I went to see him in hospital several times. My father passed away in April 2007. I also took part in his funeral. My father was permanently in hospital from January 2007 until his passing in April 2007. ? I have received confirmation that my late father did have a Will. The Will does not mention me, it was also signed 5 days before he passed away when he was in a very serious condition in hospital. The Will would have been taken to him to sign in hospital. One of my father’s brother’s was a Trustee of the Will along with my father’s wife. One of the witnesses to the signature was another brother of my father. ? I have now heard that my late father’s wife has now remarried for the third time. Her new husband and I assume his children are living in my late father’s home. ? The likelihood is that some of my father’s assets may have been transferred to either his wife, sons, brothers, sister or step children. I am writing to you to ask for a fatwa based on Sharia to cover the following issues: ? What is the family is obliged to do under Sharia? What does the Qur’an say? ? Who has rights to my late father’s estate and who doesn’t? ? What should be my entitlement under Sharia and what are the rules about not complying? ? Is the Will valid under Sharia because it was signed 5 days before my father passed away when his health condition in hospital was very serious due to cancer? ? If the family has already transferred or used some of the money, what should they now do? ? How do you suggest this matter be approached and dealt with in a fair and just manner? ? Are there any other matters/ considerations that I should be aware of? I look forward to receiving your ruling and wisdom as a matter of urgency. May Allah SWT continue to bless your work and efforts. Wa-alaykum salaam.