Short answer. Yes. You may take possession yourself, or it may be taken for you by your legal representative or your agent. Even a person with no authority at all can do it — but in that case possession is not treated as acquired until you ratify what he did in your name.
What the law says
Possession may be acquired by the same person who is to enjoy it, by his legal representative, by his agent, or by any person without any power whatever
Civil Code, Article 532 — Who May Acquire Possession. Read the full provision →
Four routes, and one of them is conditional
The article lists four people who can acquire possession for you. You, personally. Your legal representative — the parent, guardian or administrator whom the law itself puts in charge of your affairs. Your agent, someone you actually authorized. And, unexpectedly, any person without any power whatever. The first three take effect at once. The fourth does not: the law says possession is not considered acquired until you have ratified the act done in your name. So a stranger who occupies a lot and announces he did it for you has, until you say yes, changed nothing in your legal position.
What ratification does and does not do
Ratification is your adoption of an act you never authorized, and once given it makes the possession yours. This matters far more than it sounds, because possession is the raw material of several rights — the running of acquisitive prescription, the presumption of ownership that attaches to a possessor, the remedies available against someone who disturbs you. The date of ratification therefore has consequences for anyone counting time. Ratification is also a choice, not an obligation. If the unauthorized entry was wrongful, or the property carries burdens you would rather not assume, you are entitled to refuse and leave the act where it stands: as the stranger's own.
The unauthorized helper is not left in limbo
The provision ends by preserving the juridical consequences of negotiorum gestio in a proper case — the body of rules governing someone who voluntarily takes charge of another's business without a mandate. That framework can give the well-meaning intervenor a claim for necessary expenses, while also imposing duties on him: he must manage properly, and he answers for what he mishandles. So refusing to ratify does not automatically strip a genuine caretaker of every claim, and equally, someone who acted for you without asking cannot treat himself as free of responsibility for what he did.
Practical points if this is your situation
If you are sending someone to take possession, do it through a written authority that names the property and the acts allowed — it removes the ratification question entirely and is what registries, barangays and adverse claimants will ask to see. If someone has already entered in your name, decide deliberately rather than by silence, and record the decision in writing with the date, because prolonged acquiescence can itself be read as adoption of the act. Where the property is titled or a dispute already exists, have the position reviewed before you take or reject the benefit of what was done.