Short answer. No, not if it prejudices the others. Article 1209 provides that when the obligation cannot be divided, the creditors' rights can only be affected by their collective act. One joint creditor acting alone cannot release or otherwise impair the claim in a way that harms the others; the creditors must act together to give up any part of it.
What the law says
the right of the creditors may be prejudiced only by their collective acts
Civil Code, Article 1209 — Joint Indivisible Obligations. Read the full provision →
Why one creditor cannot act alone
When the thing owed cannot be split, such as one specific piece of machinery owed to several co-owners, no single creditor can be allowed to unilaterally give it up or compromise the claim, because doing so would strip the others of a right they equally hold in the same undivided object. Letting one creditor bind the rest without their consent would effectively let him dispose of an interest that was never his alone to give away.
What collective action looks like
A valid release, waiver, or settlement affecting the indivisible claim needs the assent of all the joint creditors, not just one acting on impulse or convenience. Until that collective consent exists, the debtor's obligation toward the group remains intact despite one creditor's unilateral move. In practice, this usually means every named creditor signing off on the settlement document, or otherwise clearly manifesting agreement, before the debtor can treat the indivisible obligation as extinguished or reduced.
The flip side for debtors
The same article also protects the debtor by requiring the debt to be enforced only by proceeding against all the debtors together when division is impossible, and by shielding co-debtors from covering an insolvent debtor's share. Both halves of the rule exist to keep an indivisible obligation from being unfairly carved up by one party's individual action, whether that party sits on the creditor's side or the debtor's side of the relationship.
What if the release still goes ahead
A release signed by only one creditor over an indivisible claim does not bind the others, so the remaining creditors may still pursue the debtor for the full performance of the obligation as if that release never happened. The creditor who acted alone may end up answerable to the rest of the group for whatever share of the value he improperly gave away, since he had no authority to dispose of an interest that belonged to all of them jointly. This is why co-creditors sharing an indivisible claim are generally better off putting any settlement authority, or a requirement of unanimous written consent, in writing from the outset.
Related provisions
- Civil Code, Article 1209 — Joint Indivisible Obligations
- Civil Code, Article 1207 — Joint and Solidary Liability Defined