Firstly this is a great program. I love it.

I have a main x-plane 12 and an x-plane 12 I use for betas.

How do I switch between the two with Littlenavmap

Thanks.

You can only switch between 11 and 12.

I suppose they use the same navdata and airports. So why switch at all? 
Install the Xpconnect plugin manually in both and LNM will connect to whatever X-Plane is running.

Weather will be a problem since LNM loads the METAR and GRIB from the base path set in the scenery database dialog.

You can change the base path in the load scenery database dialog manually to point to the other instance and maybe reload the library.

Alex

Thank you!