Quick Q: If I unlock higher SR tiers can my lower tier co-op friends still enter?

I couldn’t find an answer to this via search… basically can I grind to get to e.g. SR 50 and then bring my friends who have only done SR 10 along? Or will they not be permitted to enter?

Bonus question while I’m thinking about it: does unlocking SR 50 in Elite also unlock it in Normal? Or do I have to do the grind separately on each difficulty level?

Thanks!

Yes, your friends will be able to go to 50th Shard.

The stones unlocking SR levels work on each difficulty, i.e. if you got blueprint on veteran for 50th Shard for example you can use it on Ultimate to visit this shard.