R.I. Gen. Laws § 44-23.1-2 — Apportionment

Unless the will provides, the tax is apportioned among all persons interested in the
estate. The apportionment is made in the proportion that the value of the interest
of each person interested in the estate bears to the total value of the interests
of all persons interested in the estate. The values used in determining the tax are
used for that purpose.