I’m stumping on Frankie (short for Frankenstein) but I’m not gaining much traction.
This is great.
[Moderating]
This looks more like IMHO than CS. Moving.
Oh. It’s for a four-legged being.
Now the only thing that springs to mind is “Zamperl”. It’s the Bavarian word for a small (and usually energetic) dog.
https://de.wikipedia.org/wiki/Zamperl (German only)
There are theories linking Birgit to the nordic name Birger, so who knows.
It honestly depends on the priest as well. Birgit’s younger sister Astrid (now that’s definitely not a Catholic name since As- means something related to the Æsir) was baptised by a different Catholic priest, a fairly liberal guy who also happened to be her grandmother’s cousin. He solved the whole problem by invoking “Saint Astrid, if she exists”.
Thanks. The Fantasy Name Generator is an incredibly useful site if you’re even slightly creative.
How about Hannelore?
Hannelores Tag ist grau, denn Helmut Kohl schlägt seine Frau
(Hannelore’s day is grey, cause Helmut Kohl beats his wife)
Mother of Saint Olaf, king of Norway 
In general the whole “must be a saint’s name” thing was an enormous bout of stupidity anyway; after all, someone’s got to be the first saint of their name, and it’s not as if Jesse, Simon, Jacob, the other Jacob, Andrew, John, Luke et al had been raised Catholic.
Liebkuchen
Ok, not really a name. A type of cookie. But fun to say. Sounds like it might fit your pup.
“Marzipan” ia a GREAT name for a little dog, and “Marzipants” is a great nickname.
My son’s nickname/common name is Mars, and I call him “Marzipants” all the time. The dog, Phobos, is of course called “FauxButt”.
Sorry, it’s Lebkuchen, which doesn’t sound quite as nice as Liebkuchen ;). But it’s very tasty!
Picasso’s dachshund was called Lump.
I knew someone who had a Bichon called Phobos, Manda JO.
Better than Anschluss, which sounds like a dog that would appropriate all your soft, comfy furniture.
Barbarossa would be a swell name for a female Chihuahua.
Anschluss has certain connotations. For the same reason, don’t go with Blondi (Hitler’s dog)
More a term of endearment than a proper name: Liebchen.
Is it me? Our Phobos is a Bichon-Poodle mix
Sigrid
Well, I feel some obligation to explain where we landed, since I asked for your advice.
Because we “reGreta getting her.”
Just kidding.
I floated Greta but I knew a schnauzer named Greta from a different relationship. I liked Bridget but it fell flat.
I came up with Marzipan, but we couldn’t come up with a cute way to shorten it. (Marz? Marzy? Panny? ugh).
Then I came up with Penelope. It was an instant hit and the GF loved it. Until, she took the stupid little fang-tornado to her folks house and they said it wasn’t German enough. Like it *HAS *to be German. But also, there’s no cute way to shorten “Penelope,” and I believe a dog’s name needs to be as few syllables as possible (my dog is named Doug, because it’s literally the best dog name. You just add a “u.”)
Liebchen took a big lead after that, because for whatever reason the Mrs. loved the idea of calling her Libby.
It didn’t feel right, and after a lot of frustration I admitted "when I call to her I keep defaulting to “Greta.” It’s short and sweet, it fits, and I just feel like she IS a Greta.
Plus, her conservative parents won’t like that she’s named after Greta Thunberg. And so, we just decided it was so.
So meet Greta.
She’s far, far smaller than you think she is: She’s roughly the size of a grown squirrel. She’s about 3 months old.