mod_rewrite rewrite url using .htaccess php

[pedrodenim]

I am new to htaccess rules.I want a rule that will treat two urls as one.

• http://domain.com/folder/multisite/index.php
• http://domain.com/folder/multisite/sites/client1/index.php

This two should be treated as same URL. I just want to add sites/client1 to URL which actually does nothing. Every URL request should contain sites/client1/.For next request like

• multisite2/index.php?id_product=1&controller=product
• multisite2/sites/client1/index.php?id_product=1&controller=product

Thanks for any help.