How to split multi HTML files at multi locations?

I've noticed calibre is capable to split HTML file at multi locations. But it only works for the only one HTML file you opened.

What if I insert multi split markers in multi HTML files, and try to split these HTML files at one time?

BTW, the font I added in calibre edit was not put into OEBP/Fonts folder like what Sigil does. Is it possible to move file into another folder in epub container using calibre edit?