I got this working by adding empty points. I filled every series with max possible data points to begin with. Say I want to show 100 data points in every series before I start deleting the oldest (Points[0]) data point so that my chart will look like it's moving from right to left. In that case I will add 100 empty points while creating every series using:
for (int i = 0; i < 100; i++)
{
series.Points.AddXY(i.ToString(), double.NaN);
series.Points[i].AxisLabel = " ";
}
Then, while adding real data just do it normal way:
_chart.Series[index].Points.AddXY(time, YValue);
// delete more than max. points.
if (_chart.Series[index].Points.Count > MaxTrendPoints - 10) // -10 is adjustment. Got it by trial and error.
_chart.Series[index].Points.RemoveAt(0);