Is there a need to annotate the reservable property?

"The reservable character of a property is but a resolutory condition of the ascendant reservor's right of ownership. If the condition is fulfilled, that is, if upon the ascendant reservor's death there are relatives having the status provided in Article 811 (Art. 891, New Civil Code), the property passes, in accordance with this special order of succession, to said relatives, or to the nearest of kin among them, which question not being pertinent to this case, need not now be determined. But if this condition is not fulfilled, the property is released and will be adjudicated in accordance with the regular order of succession. The fulfillment or non fulfillment of the resolutory condition, the efficacy or cessation of the reservation, the acquisition of rights or loss of the vested ones, are phenomena which have nothing to do with whether the reservation has been noted or not in the certificate of title to the property. The purpose of the notation is nothing more than to afford to the persons entitled to the reservation, if any, due protection against any act of the reservor, which may make it ineffective. x x x." (p. 292, ibid)
Likewise, in Dizon and Dizon v. Galang, G.R. No. 21344, January 14, 1926, 48 Phil. 601, 603, this Court ruled that the reservable character of a property may be lost to innocent purchasers for value. Additionally, it was ruled therein that the obligation imposed on a widowed spouse to annotate the reservable character of a property subject of reserva viudal is applicable to reserva troncal. (See also Edrozo v. Sablan, G.R. No. 6878, September 13, 1913, 25 Phil. 295).
"Since these parcels of land have been legally transferred to third persons, Vicente Galang has lost ownership thereof and cannot now register nor record in the Registry of Deeds their reservable character; neither can he effect the fee simple, which does not belong to him, to the damage of Juan Medina and Teodoro Jurado, who acquired the said land in good faith, free of all incumbrances. An attempt was made to prove that when Juan Medina was advised not to buy the land he remarked, ‘Why, did he (Vicente Galang) not inherit it from his son?’ Aside from the fact that it is not clear whether this conservation took place in 1913 or 1914, that is, before or after the sale, it does not signify that he had any knowledge of the reservation. This did not arise from the fact alone that Vicente Galang had inherited the land from his son, but also from the fact that, by operation of law, the son had inherited it from his mother Rufina Dizon, which circumstance, so far as the record shows, Juan Medina had not been aware of. We do not decide, however, whether or not Juan Medina and Teodoro Jurado are obliged to acknowledge the reservation and to note the same in their deeds, for the reason that there was no prayer to this effect in the complaint and no question raised in regard thereto."
Consistent with the rule in reserva viudal where the person obliged to reserve (the widowed spouse) had the obligation to annotate in the Registry of Property the reservable character of the property, in reserva troncal, the reservor (the ascendant who inherited from a descendant property which the latter inherited from another ascendant) has the duty to reserve and therefore, the duty to annotate also.