I'm not sure but make a back-up and try, if it doesn't work, you can always load up your back-up on your new 10 person realm

We are all using Java edition, so should be fine. Thank you for your clear and helpful information 👍

The only way the OS would matter if you’re playing Bedrock/Windows 10 edition, because only Java is available for Mac OS.

I have some more friends that would like to join, so I want to upgrade it but afraid I'll lose our progress. Also, they play Mac while we currently are all on Windows, does this matter in any way? 

&amp;#x200B;

Thanks for reading

I have a 3-player realm right now, can I upgrade to a 10-man and still keep my world?