Fast EMA close, SMA high & SMA low

Hi, can someone kindly help me with this code please?

I'm trying to write a Fast EMA using Close, then a Channel = SMA high & SMA low. When I only had a Fast & Slow EMA Close, I wrote like this & all good. 

[Parameter()]
public DataSeries SourceSeries { get; set; }

[Parameter("Fast EMA", DefaultValue = 9, Group = "EMA")]
public int FastEMAPeriod { get; set; }

[Parameter("Slow EMA", DefaultValue = 21, Group = "EMA")]
public int SlowEMAPeriod { get; set; }

But this only lets me set the source to Close (or open, high, low), but one type only. Now I need 3 types - Close, High & Low. It doesn't let me put DataSeries SourceSeries in each, saying I already used it. Example below won't let me do

[Parameter("Fast EMA", DefaultValue = 9, Group = "EMA")]
public int FastEMAPeriod { get; set; }

[Parameter("Fast EMA Source", Group = "EMA")]
public DataSeries SourceSeries { get; set; }

[Parameter("SMA Chan High", DefaultValue = 100, Group = "Channel")]
public int SMAChanHigh { get; set; }

[Parameter("SMA Chan High Source", Group = "Channel")]
public DataSeries SourceSeries  { get; set; }

Appreciate your help, thanks

Sue