Routing effect sends to a Subgroup Stereo Bus

You can route your reverb bus back to the dry bus si that the dry bus volume control affects both equally, maintaining a consistent wet/dry ratio as you automate the levels.

I haven't gotten the hang of typing on my smartphone yet.

Dilaco1 - your system specs look pretty robust so you have options.
 
1. (not number 1, but mentioned first) is to not send your effects to one or more effects busses, and instead put them on the tracks.  Route your tracks to your sub busses for grouping.  Levels of your effects will correspond to what you assign on the tracks.
 
2. as Bristol_Jonesy suggested, put all of your effects on your sub busses.  The downside of this is that you'll lose any individual level control for the effects for the individual tracks using that bus.
 
3. grit your teeth and bear the problem that you described as "good enough", or, possibly go the extra mile (number 4)
 
4. I've been trying to use the following method quite a bit, but I'm not saying it's a model for others.  I have a sub bus for Drums, one for Elec Guitars, one for Acous Guitars, one for Keys, one for Vox, etc. Each of those are routed to the Master bus.  I send the output of the tracks for those categories to these sub busses. 
 
I also have an FX sub bus also for each of those.  Drums FX, E Guit FX, A Guit FX, Keys FX, Vox FX. 
 
I route the output of these FX sub busses to their corresponding overall bus (i.e., the Drums FX to the Drums bus).  I use the Grouping feature to group the volume between the pairings. That way if I lower the volume say of the Vox bus, the Vox FX bus lowers with it. 
 
Where it gets weird is I've been also setting up sub busses for the "most commonly used" effects for each category, especially reverb.   I have other effects sub busses for some of the categories such as Delay, Long Delay, and Compression (for New York Compression).  So for Guit Verb and Guit Delay and Guit Long Delay (three sub busses), they all route outputs to Guit FX.
 
From the individual track, let's say a guitar track, I route the track output to the Guit Bus, and I can have say 3 sends, one send going to the Guit Verb, with it's own individual and suitable send level and pan for that particular track, and another send going to the Guit Delay, and another send going to the Guit Long Delay. 
 
I can get it all right for that one track when it's just playing by itself, and then when I do any sub group level changes (where I change the relative volumes between Guit, Drums, Vox, Keys, etc.) the effects all stay with appropriate levels per track.
 
Having the different reverbs per category also allows me to use different reverbs.  I might use Breverb on Verb A Guit, and perhaps Valhalla Vintage Verb on the Verb E Guit sub busses.
 
Sounds like a pain, but since I have it set up in a template file there's no set up when I open a new file, it's already routed that way.
 
Just a suggestion.  I may be wacko and off the deep end.  But it's been working for me, and Sonar can handle all the busses without losing track of anything.  (As long as you have a machine that's not underpowered).