Allow a SharePoint Application to add a button on every post of a blog site

I have to make a SharePoint Online Application (on office365) that add a "Facebook Share" button on every posts of a blog site.

The solution i found so far is to replace the master page by a custom master page which add the button on every blog post with JQuery. The button then call the code of my application to share on facebook. Everything works fine with the sharing process.

Now the problems :

• The first problem is when the user have a custom master page, he lost it.


• The second problem is that i have to give all permission to the application and sometimes it can't deploy correctly on the customer site.

I think today i will try to modify the app they call "Post" to show my facebook button but i don't know if it can works.

Ask if you want more information.

I'm new on Sharepoint, any help would be greatly appreciated !