To post a form directly to a third-party platform as well as Marketing Cloud Account Engagement upon submission, LenoxSoft should use the form handler tool in Marketing Cloud Account Engagement. This tool allows them to use their own forms while still sending the data to Marketing Cloud Account Engagement. They can specify the third-party platform's URL as the post URL in the form handler settings and map the form fields to Marketing Cloud Account Engagement fields. Reference: [Marketing Cloud Account Engagement Form Handler]