Hi Doug,
I do plan to manually align the functionals to the structural as a final step, but our epi scans look different enough from our T1s that I want to use this as a starting point. Also, combining transforms is something I've wanted to be able to do a few times now as I explore different ways of looking at my data, so I think it could be useful for the future.
One thing that seems to have worked for my current case is to convert my registrations to the xfm format, add a final row to make a 4x4 matrix, multiply them in matlab, and make a new xfm file with the resulting matrix. Is there a better way to do this?
-Clark