When she died her two sons (aged 14 and 15) were left to the care of her brother, Ralph Marsh, who died himself in September, 1742.
According to the marriage banns87 she was over 25 years old when she married, which puts her birth before 1691.

In her will (according to 86, but I haven’t seen the will), she left all her real estate to her younger son, John, with the rest to be divided equally between him and Richard. No idea why.

Of Gunnersbury, Middlesex.86 His marriage banns say he was aged upwards of 30 years when he married in 1716.87