Add symetry control voltage to a low freq oscillator

[belzrebuth]

Hey all,
I was wondering how I could add a control voltage signal (say a +/-5V AC signal (triangle sine or whatever ) to a symmetry offset of a low frequency oscillator.
I attached the schematic of the LFO and highlighted the node of interest.
This node needs -6V DC for the output to be a triangle at the range I'm interested in (I don't use the other one so let's say that the summing 100k is tied to a single pot)
With about -5V I get a rev saw and -7V I get a saw so my whole range is +-1V and at mid level it needs to sit a -6V.
Now the tricky part:
I can scale a -+5V control signal to be +-1V with an inverting amplifier of 1/5 gain.
Directly feeding that +1 signal with a decoupling cap to the 100k I get a tiny amount of change at the output.
The result is almost neglible so I thought that maybe those voltages were in parallel and the bigger always wins so I tried adding that offset with another 100k going to the inverting input to properly sum them at that node but I get almost the same results!
What can I do to make it work?
Do I need to rectify the control signal and feed it as a proper offset? I don't understand why it doesn't work.

EDIT : It seems that the decoupling capacitor between my control voltage and my 2nd 100k summing resistor was loading the opamp down probably because of the vgnd there. I removed and attached the output of the scaling opamp directly to the 100k and it seems to work!