A publishing company has an existing media plan creation process that was setup using OmniStudio...

When adding a new secondary budget field required for media plan creation, the consultant should add this field to the Media Plan Placements object. This object is specifically designed to store detailed information about each placement within a media plan, making it the appropriate place to store budget-related data. Adding the field here ensures that it aligns with the rest of the media plan details and can be seamlessly integrated into the corresponding OmniScript for data capture and processing.References:https://developer.salesforce.com/docs/atlas.en-us.omnistudio.meta/omnistudio/