Short answer. The court decides, acting through commissioners. In a partition case, if the parties cannot agree on how to divide the property, the court appoints not more than three competent and disinterested persons as commissioners to make the partition, allotting to each co-owner the part and proportion the court directs.
What the law says
the court shall appoint not more than three competent and disinterested persons as commissioners to make the partition
Rule 69, Section 3 — Commissioners to make partition when parties fail to agree. Read the full provision →
Agreement first, commissioners second
A deadlock among co-owners does not leave the property frozen. The Rules of Court assume the parties will first try to divide the property themselves; the machinery of Rule 69 takes over only if the parties are unable to agree upon the partition. At that point the division stops being a matter of negotiation and becomes a matter of adjudication — the court, not the loudest or largest co-owner, determines who gets which part. No single co-owner can impose a division on the others, and none can block the process simply by withholding consent.
Who the commissioners are
The court appoints not more than three competent and disinterested persons as commissioners to make the partition. Both qualifications matter to a co-owner worried about fairness. Competent means the commissioners must be capable of the task — dividing land or other property sensibly. Disinterested means they must have no stake in the outcome: a relative of one co-owner, or someone who stands to gain from a particular division, does not qualify. If a proposed commissioner is partial, that is the moment to object, before the work begins rather than after an unfavourable report.
What the commissioners actually do
The commissioners are commanded to set off to the plaintiff and to each party in interest such part and proportion of the property as the court shall direct. Two things follow from that wording. First, the commissioners divide the property physically or by allotment — they decide which portion answers to which share. Second, they do so under instruction: the proportions are fixed by the court, based on the shares it has determined each co-owner holds. The commissioners implement the shares; they do not decide who owns how much. A co-owner who disputes the size of a share is contesting the court's determination, not the commissioners' work.
What this means for a deadlocked co-owner
If talks have genuinely failed, the realistic path is a partition case in which the court settles the shares and, absent agreement, appoints commissioners to carry out the division. Before filing, settle the groundwork a court will need: the title or documents showing how the co-ownership arose, the basis of each co-owner's share, and any partial agreements already reached. An agreed partition remains cheaper and faster at every stage — and remains possible even after suit is filed — so the commissioner route is best understood as the fallback that keeps one holdout from paralysing everyone else.