Part of the municipal park was deforested. The wild cat Mitzi, remaining orphaned with her brothers, has to leave her home destroyed by wood cutters. She reaches the Big Park Reservation (Rodnei Mountains National Park), where she finds shelter in the abandoned cottage of the forester. It’s Christmas Eve and the inhabitants of the Big Park are preparing for the celebration. Mitzi and her brothers are having trouble even here, being disturbed by the bad guys: Kit-Bandit and Max-Mask. They dress up in wolves in order to scare them away from the reservation. Their true identity is discovered by the wild cat Stripy and his friends. The scheme is foiled and to Mitzi and her brothers are offered a better life, proof that their guardian angel has not left them in trouble…

It sounds like the deforestation was the inciting incident, therefore, according to the 'Formula' tab (please check it out as it will help you) the logline could be:
After her home is destroyed by deforestation, a wildcat must protect her younger brothers in a hostile world.

This is a good start, but as stated in the 'Formula' tab, a logline needs to define a clear goal for the main character.

What is the wildcat's end game? Survival is an ongoing effort with seemingly no end in sight, what achievement will beyond a doubt signify that she has achieved safety for her brothers?

Thank you all for taking the time to write. After reading your comments, my logline would be:

"A caring orphaned wildcat has to leave her home destroyed by wood cutters and protect her brothers while struggling to survive in a hostile world."

The above members were very kind in reading your very long post and responding with their thoughts.

Here is a different type of kindness; You NEED to learn to logline your own concepts... give it a try I'm sure you'll see you can do it.
Once you've posted a logline of some sort,? you'll get far more productive responses that will actually help you.

Check out the 'Formula' tab on the top bar for a helpful starting point.

All the best.