I hope the 7th February is the 11th day hence no need to stop the masikam of your father and you can do.
Or you can club the masiyam to the next month masiyam.

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You might have done your mother shradham on the 11th day (i.e, 19th January)
if not done do it on 9th February (on Krishna Navami) or 15th February on Amavasai day without fail.