Yes, there is. There's a plugin for PI that's called DBEXtract. It is used mainly to combine stacked unstretched subs taken with an OSC, using an Ha-Oiii fllter and an Sii-Oiii filter, to simulate SHO taken with a mono camera and three filters (S, H and O). Try it and see if it produces the results you want.
There's also another method. After making an integrated unstretched image with your L-Quad filter, you can combine it with an integrated unstretched master taken with the-Ultimate filter, using the standard PI image integration process BUT--the image integration process requires at least 3 images, so make a copy of either integrated image (in your case the Ultimate or the Quad) and give it a different name. Then you can integrate the 3 images into a single integrated unstretched master, using the data from both filters.
There's a third way that involves channel separation of the Quad and Ultimate integrated images and then combining the channels into a new RGB image. I've never used channel separation in that way so I can't say much about it. Others will know more about that method.
Jerry
https://pixinsight.com/forum/index.php?threads/new-script-dbxtract.23344/