Merging into another font?

[dy]

I'm trying to merge wavefont with Adobe blank, aiming to make all chars fall back to blanks if not found in visible ranges. Right now it's done via CSS fallback technique as font-family: wavefont, blank;.

The mergefont wavefont.full.otf wavefont.otf AdobeBlank2VF.otf command corrupts the font, as described here (following adobe-type-tools/afdko#1573).

I tried patching tables via sfntedit -a cmap=cmap-13.bin wavefont.otf , as it is used here, but it doesn't work as needed.

I am wondering how did you generate the binares for the table patches and if that's possible to regenerate them somehow.

I also would like to ask for your opinion on if that's generally correct to take Adobe Blank as source for modifications and in what way would you implement last-resort technique in non-blank font?

Thanks!