Are admin files overwritable/customizable ?

Hello guys,

I'd like to know if there is a way to custom backend fields : e.g I'd like to add blogger's twitter, email, linkedin and othe social links and to do so I'm suppossed to add code line here administrator/components/com_easyblog/themes/default/bloggers/form/blog.php

But I'd like to know if this is possible without modifying the core file ??

Thanks !

Cheers