[name_f]Do[/name_f] you think people will automatically shorten [name_f]Susanna[/name_f]? Or would she get to use her name in the long form?
I like most of [name_f]Susanna[/name_f]'s nicknames, but to me [name_f]Sue[/name_f] and [name_f]Suzie[/name_f] and Sooki have a different vibe.
I do like [name_f]Zanna[/name_f] / [name_f]Sanna[/name_f], but I’m not sure how much people would revert to them. There might be some pronunciation issues too, which complicate the simplicity of the original name.
[name_f]Susanna[/name_f] is quite long, so people might shorten it when she’s young though I feel like they won’t when she’s older, especially if she corrects them immediately.
I also love [name_f]Zanna[/name_f] and [name_f]Sanna[/name_f] as nicknames for [name_f]Susanna[/name_f], but I think it’d be quite easy to get people to call her one of these instead of [name_f]Sue[/name_f]/[name_f]Suzie[/name_f]! I really don’t think it’d be an issue if you just said “This is [name_f]Susanna[/name_f], though sometimes she goes by [name_f]Sanna[/name_f]” or “Actually, we don’t call her [name_f]Sue[/name_f]. We use [name_f]Sanna[/name_f] as a nickname, it’s what she’s more used to”
I don’t see how there’d be pronunciation issues?
I have a four-syllable name that doesn’t usually get shortened (not in my native culture atleast, when I lived abroad for a few years my name was shortened almost constantly even by strangers). I also know people with two-syllable names whose names get shortened all the time. I suppose you can’t really predict it. If you continuously assert that she goes by [name_f]Susanna[/name_f]/[name_f]Sanna[/name_f] in her early years people will most likely call her that, but she may well decide that she wants to be [name_f]Suzy[/name_f] or [name_f]Zuzu[/name_f] later on. I’d just make sure that there isn’t any nickname option that you truly dislike, as she may choose it for herself at some point in her life.
On the pronunciation of Sanna - I’m not sure. Pronounce names and a few other places says Sanna the way I read it (San-na).
I have found some comments online that suggest other renditions.
I really like San-na or Zah-na so I hope my pronunciation is legit. 
People might shorten it, if they have a tenancy to nickname (which I’ve noticed some people just do). Others will call her by her full name and she (or you) can always correct people to what she prefers
I know an adult [name_f]Susannah[/name_f] who always goes by her full name, and another who always goes by [name_f]Susie[/name_f]. I think you make a choice and correct others as you go.
Some people will. But it can be easily corrected. A lot of people just like to cutesy up names. My daughter is [name_f]Lucille[/name_f] and I swear 95% of the time I introduce her to someone they say nice to meet you [name_f]Lucy[/name_f]. She doesn’t go by [name_f]Lucy[/name_f]. [name_f]Lucille[/name_f] is only 2 syllables, same as [name_f]Lucy[/name_f] so I don’t think it is even easier to say… I just let it go. But it’d be easy if people say nice to meet you [name_f]Suzie[/name_f] to say actually we call her [name_f]Susanna[/name_f] or actually we call her [name_f]Sanna[/name_f] for short if it’s something that bothers you. Or bothers her. I always correct anyone who calls me [name_f]Becky[/name_f] and I’ve never minded doing so.
Good point. I suppose there’s always a certain amount of this confusion, even when one doesn’t think it will happen. My son’s name is [name_u]August[/name_u]. People often remember his name as “[name_m]Austin[/name_m].”
[name_f]Susannah[/name_f] is so pretty. I know one and everyone has always said [name_f]Susannah[/name_f], until they get to know her…then they may say [name_f]Sue[/name_f] or [name_f]Susie[/name_f] or even [name_f]Suze[/name_f]. But in most formal settings…school, work, etc. it’s always [name_f]Susannah[/name_f].