I’m reading that you seem to be confused by the naming of some server instances in the network which is indeed called “Lemmy”. One of the servers is called “lemmy.ml” (that’s where the main developers are at home and it’s currently the one with the most users but that might change). Another one is “beehaw.org”. Both and a whole number of others are part of a so-called “federated” network, they share their “communities” with each other. So, although you are registered on beehaw.org, you can as well post to a community at lemmy.ml etc.
Ahaaa! Yes that is what i missed. It still lacks listing all communities at an instance and some other general functionality i will not iterate here, but a way of subscribing through Jerboa was what i wanted. Thanks!