Check this post: http://cjsharp.com/blog/2013/04/19/automatically-populating-page-or-block-type-properties-for-a-language-branch-in-episerver-7/
It was built for EPiServer 7.1, but there shouldn't be any difference for 7.5+
Content editors can achieve this by comparing the current published version to the published version of the master branch:
Appreciate this post is old, but iut has new comments. The Episerver Languages add-on allows you to use the gadget to create language versions prepopulated with the content from another language. Using this add-on should prevent the need for any manual compare.
We've used this quite successfully in productions sites, mostly for different english variants where we use fallback languages but sometimes need to create a UK/US specific page with minor content changes for legal reasons.
I can't post links unfortunately but a Google for 'episerver languages add-on' should bring up the webhelp for it.
When a block/page is translated the Master content(Content in master language) is not 'carried' across.
Master language is English Uk and client want to translate it in English US. on Translating US all fields are blank Is there any way to get English UK values by default before translation.