Currently, there is no possible way to add the insights tab to an existing Contact/Account/Lead form, this is causing lot of issues with projects where we are adding the Marketing module to an already configured system.

The suggested 'workaround' for this is to copy the form with Insights enabled, customise it then set it as the default form. Insights tab is already available to the OOB Contact form, therefore, you can achieve this by opening it in form editor and clicking the "Save As" button.

For an existing, highly customised form, this workaround is not feasile so it would be great if there was a way to add the insight tab component to an existing form.