From what is sounds like, Mandate is a child record of Account. So assuming you are running CRM 2014 you can use the Quick View form to show related data. But if the Mandate record is indeed a child record, you would have to do so in the form of a sub-grid
on the Quick View form - even though there is only 1 record you aren't able to display something like the first records of potentially many.
So if you go under the Mandate forms in the Customizations area you can create a new Quick View form, you can add a sub-grid from the Insert tab. From there you can choose the related entity, view, etc... Then on your Account form you can add a Quick View
form from the Insert tab and then reference the Lookup field, related entity, etc...
If you truly want data from a child record in fields on the parent, you might be better off creating the extra field and using a workflow to populate them. Alternatively you could go as far as creating an HTML/JavaScript web resource that displayed the information
as well and do so dynamically and without creating extra fields.
Jason Lattimer
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