Anna Tannekyn
pro:
I can take it in real SCA-life as two first names, it will be easier to sign with Anna (Tannekyn) Silvenhain
I like the sound
it fits to my northern german roots
con:
hard to document
Anna Silberin/Anna Severin
pro:
sounds like a very good german name
easy to remember
con:
Silberin sounds silly to me
Severin is hard to document, although I’d like it the most if it won’t be Silvenhain (or Tannekyn) at all
Anna von Staufenberg/von Streitberg/von Schönhaid
pro:
all should be easy to document
all are good german names
all contain the initials AvS, which I use very often
con:
they are far away from the original „Silvenhain“ and all of them have their own history which isn’t necessarily mine.
nauta historiae 
Severin was a very popular saint in the Scandinavian countries – have you looked in Swedish, Norwegian, or Danish sources for the name? You might be able to document it that way.
Personally, I really like <Anna Silberin>; I don’t think it sounds silly at all, I think it has a lovely soft sound to it.
I’m not so fond of <Anna Tannekyn> – not sure why, I can’t really articulate it, but it just sounds a bit too nasally, at least when I say it.
Good luck in choosing!
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