How old is your pediatric subject? Collaborators have had success using the standard pipeline from about 4.5yrs of age. You do not need a new / different template in case you want to process that population. You might however want to read about some child-specific manual edit recommendations: 
https://surfer.nmr.mgh.harvard.edu/fswiki/ChildBrainManualEdits

Lilla

From: Greve, Douglas N.,Ph.D. <DGREVE@mgh.harvard.edu>
Sent: Tuesday, November 29, 2022 9:46 AM
To: freesurfer@nmr.mgh.harvard.edu <freesurfer@nmr.mgh.harvard.edu>; Zollei, Lilla,Ph.D. <LZOLLEI@mgh.harvard.edu>
Subject: Re: [Freesurfer] Creating or Using Alt Templates
 
You don't need a different template for the surface-based analysis. I'm not sure about the volume-based analysis. I'm cc'ing Lilla in case she wants to weigh in.

On 11/24/2022 11:53 AM, Olivier Brown wrote:

        External Email - Use Caution        

Dear Freesurfer experts,

I am using a pediatric sample for my study. I understand that the default template has been used with younger samples in the past. However, is there a command or flag to input an external template, such as the MNI? Otherwise, is there a method for creating my own template using the acquired imaged with Freesurfer? I cannot seem to find many resources online for selecting alternate templates in the preprocessing steps of recon-all.

Warm regards,
Olivier Brown

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