What should I do to a person who cheated on my dad’s partnership?

Assalaam Alaikum,

My Question is related to my father business partner. My Father Invested money into a business (Construction) in partnership. Investor was my father and his partner was working partner after many business deals he never disclose the actual profit of the business. My father passed away couple of year back and he only gave us lump sum amount which is very small without telling the truth and disclosing the turnover for last 25 years.Now he is very rich man and performs Umrah 2-3 times in a year and perform Hajj every year.Many times he gave false promises to my father when he was alive that your partnership is here in this property and that property but never gave in writing. One of the property belongs to my father he sold out without taking the permission of my father.

What should be the solution for this now because we don't have enough money to buy house and do some business.

How to deal with this person and get the actual partnership profit amount which my father invested with him.

My father invested money based on the trust but he took the wrong advantage of it this is not acceptable in Islam which i believe.

Please give your advise on this issue.