Only 2 heirs named in the will, how will the $345K in ets be divided?

Generally this money will be divided between her surviving children. Not her grandchildren or great-grandchildren. The executor will be in charge of the distribution but the decision of who will get the money will be made by a probate judge. The executor is also in charge of getting you and your twin your $5,000 so maybe you better find a way to speak to him.