Create a 1 to Many Custom Object
Click Admin, and in the tree, select Database Management > Marketo Custom Objects.
Click New Custom Object.
Enter a display name. The API Name and Plural Name populate automatically. Enter a description (optional).
Pull the Show in Lead Detail slider over to display Show if you want to view custom object data on the Lead Database page. Click Save.
The custom object information displays the content you entered. Notice that it's in a Draft state. The next step is for you to add fields to build out your custom object.
Create a Many-to-Many Custom Object
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