This is a potential FAQ for dataset owners. Right now we do not have a nice UI for receiving patches, but it is possible to accept pull requests from GitHub.
Suppose you have dataset DS=ds001234 and someone has opened a PR openneurodatasets/ds001234#1:
DS=ds001234
PR=1
git clone https://openneuro.org/api/git/$DS
git remote add github https://github.com/openneurodatasets/$DS
git fetch github refs/pull/$PR/head
git merge --squash $FETCH_HEAD
git push
Open to considering other locations than the FAQ...