How to add Mashup to new Tab in C4C

Hello all,

I have created a new tab in Ticket's business object, called 'Phone Calls', as you can see:

Now, what I am struggling to do is to add either a mashup or a simple table inside 'Phone Calls' tab.

I do not understand why I can only add fields/mashups in the Overview section.

PS: this is not a requirement for a project; I am just genuinely curious of this unexpected behavior.

Thank you in advance.

Best regards,

Gabriel