Inserts a point into a series keeping the path sorted by time
TimeSeriesInsert[tes, {t, val}]
TimeSeriesInsert[tes1, tes2]
ts = TimeSeries[{6, 11, 17, 22, Missing[], 34, 35, 36, 44, 48}, {1}]; ts[5]; TimeSeriesInsert[ts, {5, 27}]
→ TimeSeries[{{1, 6}, {2, 11}, {3, 17}, {4, 22}, {5, Missing[]}, {5, 27}, {6, 34}, {7, 35}, {8, 36}, {9, 44}, {10, 48}}]