Hello,
1. You can certainly challenge the WILL that was fraudulently obtained by your maternal uncle.
2. Once the will is challenged you also need to move the court to get the property partitioned properly.
3. You can also file a petition along with the above obtaining a restraining order or a stay preventing the uncle/s from alienating or creating any third party rights.
4. Of the properties that have been already sold too you can move the court to be adequately compensated to accommodate the extent of the value of your share.
5. Your mom should be the petitioner in all the applications.
6. Engage a lawyer locally who can assist you.