for SVG, I cheat
(Assumes all images are the same size)
Add
all the Images using ADD Image Files
Add 1 image as the Cover :Tools: add cover: (select image)
Then copy the entire contents of the coverand paste THAT into a new file: Edit the IMAGE filename
only to the next image
Repeat
Finally: Add the REAL cover.Xhtml file
Add a Header (can be hidden or .0001pt high) if you want Sigil to generate a TOC
Alternate: the 'rolling cover add'
I do the Placement work sort of backwards
Add the LAST image as a
cover. Tools:Add cover
In the file browser:
Rename the file to its real desired name (not cover)
Add Semantics: click Cover to remove the tick
Add the Next 'cover'
Repeat the above until done