DateTime.DateFormat = "yyyy-MM-dd HH:mm:ss"
Dim t As Long = DateTime.DateParse("2020-03-08 09:00:00")
Dim strTime As String ="08:15"
Dim strArray() As String =Regex.Split(":", strTime)
Dim p As Period
p.Hours = strArray(0)
p.Minutes= strArray(1)
Dim t2 As Long = DateUtils.AddPeriod(t, p)
Log(DateTime.Date(t2)) 'displays: 2020-03-08 17:15:00