The events and timelines you see are always only what your own time machine knows about!
Of course, time agents don't have to work alone! Here, your sidekick has already prepared a merge for you! You can use the "pull" card to transfer it to your own machine.
Then, add another event on top, and "push" the result, to transfer it back to your sidekick!
[setup yours]
echo "Just woke up. Is hungry." > tom
git add .
git commit -m "The beginning"
git checkout -b pancakes
echo "Had blueberry pancakes with maple syrup for breakfast." > tom
git add .
git commit -m "Pancakes!"
git checkout -b muesli main
echo "Had muesli with oats and strawberries for breakfast." > tom
git add .
git commit -m "Muesli!"
git checkout main
git push -u sidekick main pancakes muesli
[setup sidekick]
git checkout main
git merge pancakes
git merge muesli
echo "Had pancakes with strawberries for breakfast." > tom
git add .
git commit -m "Let's make this breakfast compromise" --author="Sidekick <sidekick@example.com>"