In the US, there is really no such thing as "inheritance" tax. Instead, taxes are placed on the estate of the deceased if the estate exceeds a certain value. That value is currently set at $2 million, so it sounds like your father's estate would probably be exempt from estate taxes. Someone will, however, have to file a final tax return on behalf of your father and pay any taxes he may have owed for the year he passed away, or claim a refund on his behalf if one is due.
Since your father had a will, there is no problem for you to combine his accounts and divide the money equally among the siblings. There will be no federal tax due on any of the income distributed to the heirs.
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