Me. Stat. tit. 14 § 6655
If, in an action to quiet or establish the title to land situated in this State or to remove a cloud from the title thereto, the plaintiff, or those under whom he claims, has been in uninterrupted possession of the land described in the complaint for 4 years or more, claiming an estate of freehold therein, and seeks to determine the claims or rights of any persons who are unascertained, not in being, unknown or out of the State, or who cannot be actually served with process and made personally amenable to the decree of the court, such persons may be made defendants and, if they are unascertained, not in being or unknown, they may be described generally as the heirs or legal representatives of A.B., or such persons as shall become heirs, devisees or appointees of C.D., a living person, or persons claiming under A.B. It shall not be necessary for the maintenance of such action that the defendants shall have a claim or the possibility of a claim resting upon an instrument, the cancellation or surrender of which would afford the relief desired; but it shall be sufficient that they claim or may claim by purchase, descent or otherwise, some right, title, interest or estate in the land which is the subject of the action and that their claim depends upon the construction of a written instrument or cannot be met by the plaintiffs without the production of evidence. Two or more persons who claim to own separate and distinct parcels of land in the same county by titles derived from a common source, or 2 or more persons who have separate and distinct interests in the same parcel, may join as plaintiffs in any action brought under this section.
14 M.R.S. § 6655