Write off accrued interest from interest income

My mother purchased a US government bond maturing 2019/04/15. The purchase date was 2018/04/13, so there were 2 interest payments attributed to 2018 (2018/04/15 and 2018/10/15), but the interest payment made on 2018/04/15 to my mother is associated with an offsetting accrued interest as the bond purchase settled 1 day earlier than the interest payment date.

When I do her taxes for tax year 2018, I enter Box 15 of the T5 into Line 121, but would I be able to claim an interest expense deduction on Line 221? This expense is not shown on any tax slip, but it is on the “Investment Income Summary” the bank issued along with the T5. If the CRA questions the legitimacy of this expense, can I send them that page showing the date and amount of interest paid?