Give that there are often multiple sublemmets(communities) for a subject/hobby, I am sorely missing the ability to group them together as desired.
I hope it will be added soon to Jerboa (but also most if not all other clients) because it feels counterproductive/annoying (especially for new users) to subscribe to several mostly-identical communities but each on a different instance.
Being able to create a sort of group I could name “XYZ” for example where I could gather the contents of xyz.instance1, xyz.instance2 and x-yz.instance3 would make fragmentation much easier to deal with and reduce the risks of communities deserting due to low population/engagement.