My issue was not in being able to identify which rows are from what
source book, but specifically allowing the master workbook to get new
rows entered in the source. For example, source workbook 1 has the
following:
ColA ColB ColC
XXX BBB 999

Source workbook 2 has following:
ColA ColB ColC
PPP UUU 111

So the master has this view:
ColA ColB ColC
XXX BBB 999
PPP UUU 111

When Source Workbook 1 gets a new row, like -

ColA ColB ColC
YYY NEW 989

I need the master to get that new row, and using Copy, Special Paste,
Paste Link, the only way I know to get it is to initially copy more
than the row that is populated, and this means having a master workbook
with a lot of padded empty rows to allow for the additional rows in the
source workbooks.

Hopefully this makes it clearer.

Thanks!