R.I. Gen. Laws § 18-4-30: Representation by person having substantially identical interest.

In any action involving wills, estates, trusts or fiduciaries in the Probate Court or the Superior Court, a minor, an incapacitated person or an unborn or unascertained person whose identity and location is unknown and not reasonably ascertainable, unless otherwise represented, may be represented by and bound by another having a substantially identical interest with respect to the particular question or dispute, but only to the extent that:

(1) The person’s interest is adequately represented; and

(2) There is no conflict of interest between the representative and the person represented.