[Tu Tran]

Hi,
Yes, you can create one or more child theme of the Sns-Nazic theme.
First, you create template, layout for childthem (you can copy and custom from Nazic theme)
app\design\frontend\sns_nazic\childtheme\template
app\design\frontend\sns_nazic\childtheme\layout
Then, you can create style for childtheme (you can copy and custom from Nazic theme)
skin\frontend\sns_nazic\childtheme
After that, you configure in Configuration >> Design >> Theme to set child theme.
Please see in attachment files for more clear.
Thanks,

Attachments:

1. 

   childtheme-template1.png
   

2. 

   childtheme-style.png
   

3. 

   configue-childtheme.png
   

4. 

   childtheme-template.png