Can we have a shortcut for split subtitle in the middle, merge second-half with the next line?

[TrollFeed]

I clean up a lot of machine transcribed subs, the thing that annoys me is when sentence segmentation is off by just one or two words.
Can we have a shortcut for quickly split+merge subtitles with just one command?
I'd like to be able to put my cursor in the middle of a sentence, have it split into two, the second have is merged with the sentence below it, using just one command.