Mo. Rev. Stat. § 429.290

After any such equitable action is commenced, the same shall be exclusive of other remedies for the enforcement of mechanics' liens, but until such action is brought, the other remedies provided for in sections 429.010 to 429.340 shall remain and exist. And the procedure in any such equitable action, except as herein otherwise provided, shall be governed by the law and rules of procedure in civil actions generally.