Overlay "a part"

[color]

I have two videos, both are almost similar, the bigger resolution has a logo, and the other has a logo on another place in lower resolution (img-size).

I want to replace a part, and it works great..however, I want to make it better.

Is there a way to "fade" out the edges. So its not a hard edge when overlay like this?

UNDER=LWLibavVideoSource("under.mp4")
OVER=LWLibavVideoSource("over.mp4").Lanczos4Resize(1920, 1080).Trim(1,13547).Crop(1730,70,-80,-950)

Overlay(UNDER, OVER, Y=70, X=1730, mode="blend", opacity=1.0)

[Reel.Deel]

Something like:

msk = Blankclip(over, color_yuv=$FFFFFF, pixel_type="Y8").Crop(1,1,-1,-1).AddBorders(1,1,1,1,color_yuv=0).Blur(1.5)

Overlay(UNDER, OVER, mask=msk, Y=70, X=1730, mode="blend", opacity=1.0)

[color]

Something like:

msk = Blankclip(over, color_yuv=$FFFFFF, pixel_type="Y8").Crop(1,1,-1,-1).AddBorders(1,1,1,1,color_yuv=0).Blur(1.5)

Overlay(UNDER, OVER, mask=msk, Y=70, X=1730, mode="blend", opacity=1.0)

Yes, thank you. :)