It's good that you were able to safely assess that it's not safe to have Mio out at the same time. We always encourage members to keep dogs and cats away from their birds as there are far too many sad posts about budgies being injured or killed.
It's great to see how you were able to see the danger signs.
The picture of Shira as a puppy is so cute. Those cute little puppy eyes.... so sweet!
I'm glad you've recognized it is critical that the budgie be safely in its cage or Shira be enclosed in a different area of the home when you go to visit your sister.
It only takes a moment of inattention for a tragedy to occur.