Extracting Ha from dual band data to blend into RGB image

[OK Apricot]

I used my 533MCPto gather a couple hours of data on M31 in Ha/OIII to compliment the broadband data, but having spent a few hours on it tonight I'm struggling to find a way to blend the nice red clouds into the RGB image. I use DSS and PS CC. 

I have processed the broadband stack to a point where it's nearly finished, and the dualband stack as far as it will reasonably go without making things messy. I've tried simply blending the two images, copying the red channel of RGB into the red channel of the dualband image, then copying that back to red channel RGB, but seems to be no good. 

Does anyone here have any tips? Any work flows that I could borrow? 

Cheers 🙏