Hi Anthony,

So why is it that you need a template surface for? There may be different
solutions for what you need to do. To create an average surface model for
all these volumes, you could follow Veronica's recipe. In particular:
1- Align the volumes to a common reference volume. That reference
volume could be one of the children's volume. Preferably an AC-PC aligned
version of one volume. (3dWarpDrive, FLIRT, whatever rocks your boat...)
2- Average all aligned brains to create an average volume. If you have
one of those already you could skip the first part. (3dMean)
3- Repeat alignment of each child's original volume with the average
volume which is now your template. You could repeat 1-3 until the average
volume stops changing.
4- Create surface models with SureFit, FreeSurfer, etc.
4.5- Warp surfaces to a template (FreeSurfer) or based on Sulcal
Landmarks (Caret).
5- Create standard mesh versions of all the single subject surfaces.
(MapIcosahedron, see section 'K. Surface-Based Cross-Subject Analysis:' at

[afni.nimh.nih.gov])
6- Average all standard-mesh surfaces to create an average surface
template.

As you can see it is not that easy to create a surface template and there
might be more appropriate means for generating it then what we are
suggesting here. It all depends on what you want to do with the template.

cheers,
-ziad