make a chart as per the approx timing like morning evening or night time put random timing like if afternoon then try with 12:15 pm to 15:30 pm in gap of half an hour…check the lagan or rising sign and the planetary placements and your mums life events the major planets will not move much as they are slow movers…make sure to check transits if any on that particular date and accordingly switch the timings…then try to predict or compare marriage and child birth years…the lagan that matches the events is the timing of her birth…if you want share with me I will try to match …if u can list major life events then basis that we can reverse engineer the chart ascendant and planet placements…i had done it for few natives…so I could try for your mum if needed…jai mahadev maa gauri…