\includepdfmerge instead of
It inserts pages of several external PDF documents. It should allow
nup=2x2 as part of its options.
pdfpages manual, page 8:
<key=val> -- A comma separated list of options using the
A comma separated list of filenames and optional
<page spec> specifiers. A
<page spec> can be everything
pages accepts. Leading and trailing spaces
of items in the list is stripped.
So if you want to have pages X till Y from
A.pdf and pages Z till V from
B.pdf in a 2x2 grid use:
Will first use pages 1 and 2 of
A.pdf and then pages 1 and 2 from
B.pdf in a 2x2 grid.
Guessing from your example code in your comment I guess you need the following:
(I broke it over several lines for readability, which is not required in your document.)