P.R. Laws Ap. tit. 32A, § III, Rule 58.5
If a defendant has no objection or defense to the taking of his property, he may serve a notice of appearance designating the property in which he claims to be interested. Thereafter he shall receive notice of all proceedings affecting it. If a defendant has any defense or objection to the taking of his property, he shall serve his answer within twenty (20) days after the service of notice upon him.
The answer shall identify the property in which defendant claims to have an interest, state the nature and extent of the interest claimed, and state all his defenses and objections to the taking of his property. A defendant waives all defenses and objections not so presented, but at the trial of the issue of just compensation, whether or not he has previously appeared or answered, he may present evidence as to the amount of the compensation to be paid for his property, and he may share in the distribution of the award.