Git merge updated WordPress plugins

I have a few WordPress plugins which required updates. I know that there were changes to the plugin files made by myself and others which would be overwritten by updating the plugins. I don't know where all changes were made since other people made some of them.

I updated plugins and pushed them to a separate branch. So, I had the master branch with all the changes made to the plugins, and an updated branch which overwrote those changes. I merged both branches together and there were no conflicts.

Am I right to think that the changes previously made to the plugin files have been successfully merged with the updates or is it likely I lost some of them?

The git branches look something like this:

           -----Updated Plugins----
          /                        \
         /                          \
------Master-----------------------Merged Branch----

via Chebli Mohamed