Changing windows and balcony doors

I’ve just been notified that a lot owner has changed common property in their unit. The Sliding balcony door and all windows (they claimed they were all damaged during their renovations) 

the issue is the windows were common property and now open outwards not sliding 

I would think if they were sliding and the same colour no one would have an issue but the outward opening has annoyed the block.

what can we do to get them to change to sliding doors?

also we will look for them to pay for a bylaw to say these are now their issue if there are leaks as currently it’s been body corporate (1970’s build)