EMG BTC Control Preamp + Lipstick + Piezo + Stacked Knob

Hello, i want to add some piezo and a preamp on an ABG.
It's a Resonator bass (Regal RG-05E) that come with passive Lipstick Pickups (no infos).
I dont want to drill any holes on the body, it has 2 knobs (Tone/Volume).
I figured out that stacked knob could do the trick, but still not sure on what kind of configuration. (Volume/Volume + Bass/Treble or Volume/Blend + Bass/Treble)

I was thinking putting the EMG BTC Control cause im familiar with it on my Electric.
And adding this Schatten RG-03 piezo for Resonator Guitar and keeping the stock lipstick pickup (didn't found any better reference for now)

Im confortable with soldering i've done some repairs on an passive bass in the past and fixed some Handheld Consoles, but's thats about it with my history with bass electronics. So my questions might seem a bit dumb.

How should a wire this ? what kind of stacked pots i should use (250/500) ? and is there anything to check before connecting the two pickups together on the BTC Control ? Am i suppose to ground an ABG resonator ?

Thanks.

 

Thanks @ctmullins let me see if i get this right.
The piezo is wired to that buffer, then wired to the EMG CT Preamp with the magnetic pickup.
The magnetic pickup doesn't need to be wired to the buffer.

But it seems wrong.
There's two versions of the buffer one with one 9V battery and another with two 9v for active electronics.
So im kinda confused.

 

@ctmullins that's very nice thank you, i could use a diagram.

Since i have only 2 holes available (sounds dirty said like that)
Do you think that blending the pickups with a double volume stacked pot could work ?
I mean like a Volume for the magnetic and Volume for the piezo.
Or just a Master Volume + Blend would be better ?

 

When i said blend i was thinking with stacked pot with a Master-Volume but maybe im getting it wrong.
I would rather avoid going to a luther just to drill a hole in my ABG, and im not confident with doing wood work on an acoustic by myself. (Plus if i can avoid altering it too much, its always cool)

 

Thanks i get it better now.
Could a Stacked pot with Push/Pull and Volume/Volume could exit the switch/blend ?

 

Well i guess if i want the BTC i have to go to a luther.
My local luther is a drunken butcher, so i might need to go farther from my home :')
But it seems i can't avoid the drilling part...

I thought i could do the blending manually with a double volume stacked pot.
My first bass was an Ibanez GSR200 that got two separate volume knobs for the precision pups and the jazz bridge i guessed wrong that it would work the same if they where stacked.

Thanks for your help.

 

I guess i can always try in that configuration, and then if it doesn't work like i want.
I could go to the luther for the three hole configuration.