Hi Allison,
On the Report Object, use the properties PaperSourceFirstPage and PaperSourceDefaultPage to tell the Report where to print the overflow lines. It will print the check(and stub with up to 10 lines) to the tray that PaperSourceFirstPage is pointing to and the subsequent pages will print to the tray that the PaperSourceDefaultPage is pointing to. Then, you can stock the 1st tray with Check Stock, and the second tray with regular paper.
Jon Long
ArcherPoint