Coloring a "fit_" wave the same as the data wave

I have generated a function to color the waves on my top graph in a rainbow gradient, but if I run the function after I have plotted the fit_ waves, they are included in the gradient and are different colors from the data they are fitted to.

I have played around with using less direct methods to color the fit_ waves to be the same as the data, but it is not quite what I want and there are several instances where I could see it failing. 

Is there a way to have my function to color the wave name, then do an if/then if there is another wave on the graph that contains the "fit_" appended?

Below is my coloring function and how it is set up for reference. In order to get this version to function, I have to interlace the wave order so the the fit waves followed each data wave. The last two lines are what allow this to work.

Function GradrainbowFits() : GraphStyle
//Makes rainbow gradient between roy and biv (with a lil g in between)
//Input GradRainbow() for example
	GetWindow kwTopWin, title

	ModifyGraph/Z mirror=2
	ModifyGraph/Z lSmooth=1,lHair=1,minor(bottom)=0
	ModifyGraph/Z lsize=2
	Variable i,r,g,b
	Variable j =  ItemsInList(TraceNameList(S_value,";",1))-1

   Make/O/D red = {65535,0,0}
   Make/O/D orange = {65535,42405,0}
   Make/O/D yellow = {65535,55255,0}
   Make/O/D green = {0,51120,0}
   Make/O/D blue = {0,0,65535}
   Make/O/D indigo = {19199,0,33279}
   Make/O/D violet = {38036,0,54227}


   Make/O/D w = {0,0,0}
   wave c1 = red
   wave c2 = orange
   wave c3 = yellow
   wave c4 = green
   wave c5 = blue
   wave c6 = indigo
   wave c7 = violet

	for(i=0;i<=j;i+=1)
		if(i<(1/6*j))
			w = c1-(c1-c2)*(i/(j/6))
			endif
		if(i==(1/6*j))
			w = c2
			endif
		if(i>(1/6*j))
			if(i<(2/6*j))
				w = c2-(c2-c3)*((i-j/6)/(j/6))
				endif
			endif
		if(i==(2/6*j))
			w = c3
			endif

		if(i>(2/6*j))
			if(i<(3/6*j))
				w = c3-(c3-c4)*((i-2*j/6)/(j/6))
				endif
			endif

		if(i==(3/6*j))
			w = c4
			endif
		if(i>(3/6*j))
			if(i<(4/6*j))
				w = c4-(c4-c5)*((i-3*j/6)/(j/6))
				endif
			endif

		if(i==(4/6*j))
			w = c5
			endif
		if(i>(4/6*j))
			if(i<(5/6*j))
				w = c5-(c5-c6)*((i-4*j/6)/(j/6))
				endif
			endif

		if(i==(5/6*j))
			w = c6
			endif
		if(i>(5/6*j))
			if(i<(6/6*j))
				w = c6-(c6-c7)*((i-5*j/6)/(j/6))
				endif
			endif

		if(i==(6/6*j))
			w = c7
			endif

		r = w[0]
		g = w[1]
		b = w[2]
		ModifyGraph/Z rgb[i]=(r,g,b)
		ModifyGraph/Z rgb[i+1]=(r,g,b)
		i=i+1
	endfor
	
End