(case involves title dispute to farm property; decedent died intestate in 1995 owning 120-acre farm, but had executed power of attorney in 1978 concerning the farm; decedent added agent (decedent’s caretaker) as joint-tenant owner of farm in 1992 and agent added spouse as joint-tenant to farm later in 1992; decedent’s heirs challenge to POA fails because agent had power to “manage” the property just as the principal would; but heirs’ breach of fiduciary duty and undue influence claims remanded because trial court improperly ruled such claims barred by 3-year statute of limitations; actions involve attempt to quiet title and 15-year statute of limitations applies).