Maybe your step still incorrect

I've merged migrate-engine-name into migrate-engine-name-2 and created a PR

Maybe your step still incorrect

It looks like you create the branch from your own branch dev, not upstream dev?

I've merged migrate-engine-name into migrate-engine-name-2 and created a PR

It will inhert the commit history

I viewed the changes file, this branch looks correct

nice

There is a way to merge all commit into one:

# find the latest commit hash of upstream `dev`
git log

# reset without local changes reverts to the hash
git reset --soft <latest commit hash of upstream dev>

# Now you can only add on commit to your local branch
git commit -m "Example commit message"

And you don't need do it at this time, I will use Squash and merge button to erase unnecessary commits history by github automatically.

Search "adxe" (0 hits in 0 files of 1251 searched) done with core you can merge now.
ci is failing because of extensions I will do the replacement later

And the android ci failed because you change the engine adxetools.gradle which is depended by all tests & template projects