Thanks for your suggestions
Working through handing a project back and forth, we found that there is one .settings file that is vital...
<proj name>/.settings/language.settings.xml
This worked well for .gitignore additions with the above exception:
# MCUXpresso Workspace Level
/.metadata/
/*logs/
# MCUXpresso Project Level
*.axf
*.su
*.o
*.d
*.map
*.bin
/.settings/