Use LaTex as a PDF manipulation tool
\documentclass[letter]{article}
\usepackage{pdfpages}
\begin{document}
\includepdf[pages=1-]{/Users/pmccann/Desktop/1.pdf}
\includepdf[pages=4-6]{/Users/pmccann/Desktop/2.pdf}
\includepdf[pages={4-5,10-14}]{/Users/pmccann/Desktop/3.pdf}
\end{document}