Short answer. No. Under Article 56 of the Family Code, collusion between spouses to obtain a decree of legal separation is an express ground for denying the petition. A court that discovers the parties manufactured or agreed upon the facts supporting the petition must dismiss it. Legal separation requires genuine, independently established grounds — not an agreed-upon script.
What the law says
Where there is collusion between the parties to obtain decree of legal separation
Family Code, Article 56 — Grounds for Denying Legal Separation. Read the full provision →
Collusion as a bar to legal separation
Article 56 of the Family Code lists the grounds on which a petition for legal separation must be denied. Ground 5 is collusion: the petition shall be denied where "there is collusion between the parties to obtain decree of legal separation." Collusion in this context means the spouses have cooperated — whether formally or informally — to fabricate, exaggerate, or agree on the factual basis for the petition so that the court will grant a decree. It is precisely the kind of shortcut your question describes: agreeing on what facts the court should hear to speed things along.
Why collusion is prohibited
Legal separation is not a purely private matter between spouses. Philippine law treats marriage as an institution with a public dimension, and the State — represented in legal separation proceedings by the public prosecutor — has an interest in ensuring that the decree is based on genuine grounds. Allowing spouses to script the facts and present a fabricated or agreed-upon case would turn the court proceeding into a mere formality and circumvent the law's policy of maintaining marital bonds unless a true statutory ground exists. The prosecutor's role in legal separation proceedings is specifically to detect collusion, so the mechanism for catching it is built into the process.
Other related bars under Article 56
Collusion is one of six grounds for denial in Article 56. Related grounds include: where the aggrieved party "has condoned the offense or act complained of" (forgiving the conduct bars the petition), where the aggrieved party "has consented to the commission of the offense" (agreement in advance eliminates the grievance), and where there is "connivance between the parties in the commission of the offense or act." Connivance is distinct from collusion: connivance is cooperation in causing the ground itself, while collusion is cooperation in presenting the case to the court. Both are bars. Additionally, if both parties have given grounds, or if the action is barred by prescription, the petition fails.
What this means for spouses seeking legal separation
Legal separation requires that the ground be genuine and that the aggrieved party pursue the case honestly. Coordinating stories with your spouse, signing a joint statement of facts for the court, or agreeing not to contest certain allegations — when that agreement is designed to manufacture or simplify the factual basis rather than reflect the truth — puts the petition at risk of dismissal. This does not mean spouses cannot both participate in proceedings or that a non-contesting respondent is automatically colluding. But there is a clear line between a respondent who genuinely does not contest the facts and spouses who are engineering a cooperative proceeding to get a result the law requires must be adversarially tested.