You'll have to see a solicitor with a view to raising an action of count reckoning and payment against both executors. This is where you sue for what you think is due to you as a beneficiary but the side effect is that your sister will have to provide an accounting to the court of her actions as executor. You may also want to raise proceedings for damages in respect that she essentially stole money from your mother whilst she was alive and therefore that has effected the amount of your inheritance. There are several ways that this could be done and your solicitor will advise of the best way to deal with this in your own circumstances. I hope that helps. Please leave a positive rating so that I am credited for my time.