Any proof needed for Deductions under 57 iia?

Dear Sir/Madam,

My aunt receives family pension. The monthly amount is credited to her bank account. As such being family pension there is no form 16 or so.

She wants to include deduction of Rs 15000 under 57iia in ITR1. Her total family pension is about 1Lakh / year so 15000 deduction is I believe valid.

Is just claiming  that amount of 15000 under that section in ITR1 enough? In case Income tax dept queries, what do we show them? The bank statements that the family pension got credited to her account in that FY?

Thanks and regards.