My wife and I purchased our first house a few years ago. It had beautiful landscaping that the previous homeowners had installed 10 years prior and left to overgrow a few years before we purchased. Unaware what most the plants were or how to properly care for any plant, I decided to prune back all the over grown plants.

Part of the pruning included a handful of Dwarf Alberta, which I was only made aware of what they were when I found a tag in one of the plants. After some careful investigation I learned that I may have improperly pruned the plants, which probably didn't need any pruning to begin with.

I accidentally pruned a few bare spots into a couple of them. I learned to my dismay that the plants will not get new growth if you cut back to far. I also learned that one of the plants must be nearly 30 years old as it is 11-12' tall.
This all happened about three years ago. Since then I have not touched them with any pruning sheers. I have been hoping that the over pruned spots would come back but they haven't.

Is there anything I can do to cover them up? Specifically on the large tree which is so beautiful. This tree has about 2-3 spots that are about 8-10" bare. Is there anything I can do to stimulate new growth on these branches? If not, can I wire other branches together to help fill the spots?
If needed, I can try to post pictures, although the tree is covered in snow already.

Thank you for your help!!