I'll eventually put up info on various of my attempts to portray Mystara in a Birthright System. My starting point was Solmyr works, and to a lesser extent that of Rob's SC varient, but I've been refining it in various versions for quite some time (currently working dually on Versions 4 & 6).

My 1st version was basically as Solmyr's conversion, with some stuff added based on Rob's modifications to the Savage Coast

My 2nd version I only changed slightly from Solmyr's. I added to, but never reduced, replaced, nor removed anything of Solmyr's. Added Some minor flavor text. Expanded to a few new area's (ie the Alatians)

My 3rd version was were I finally started to make significant changes and departures from Solmyr's base. I briefly had a PBEM of this version. This was the first time I got confortable enough to tweak Solmyr's holdings.

My 4th version, is the most complete form I've compiled and is one I'm still actively working on. I systematically went through every entry I had. I've got most of the Known World (Thyatis is not yet complete) and some places elsewhere (erratically) completed.

My 5th version was basically a disaster I'd like to forget about. I tried to add in too many new rules and too many micro-details. This was also my first attempt to break away from Solmyr's maps.

My 6th version is an attempt at adding the RoE style holdings (Manor's & Trade) along with some rules mods like the Silveras style mods (which I had also tried in v5). This is the other version I am still working on, but I've just started.

I'll add more notes when I have more time.

For now, I have entries up on Alfheim & The Broken Lands, as well as a (very) Rough draft of Darokin

— Greg Weatherup

Marco Fossati is also doing an Alphatian version.

Thus far see Alphatia BR: Ambur or His website

A version for new sources and true realm magic is being discussed at the piazza. Rather than adapting the Birthright rules and flavor, it is a discussion of how to keep cerillian flavored source holdings and realm magic that are still appropriate for a mystara setting. Discussion Here