add extra slide on the default slider

Are you using default blog as home or static page as home? Try using i-trans slider instead of default theme slider.

there are limitations of using default theme slider because of issues like translation and non transferable content.

you can create your custom blog page with shortcode

[tx_blog items="10" columns="2" showcat="show" category_id="" show_pagination="yes" carousel="no"]

example : http://www.templatesnext.org/icreate/?page_id=824

and here is how you add the slider
http://www.templatesnext.org/icreate/?page_id=667