She does not have to be secretive - she has no enemies, her world is accustomed to the introduction of strange wonders and will not fall apart with any revelation. She revives a large number of dead people - although none of Marianne's direct ancestors - and sends them home to surprised but happy families. She renders a larger number of people torchable. She sends letters to the monarchs of neighboring realms indicating that she is available to help with any unusual difficulties in which they may find themselves, and that she would appreciate introductions to their farther-flung neighbors. That is the "a lot".
But her world is made of cotton candy, and she has no intention of dumping a bucket of water on it in the hopes of rinsing off small amounts of dust. She is not usurping her mother-in-law, she is not conquering miscellaneous other kingdoms, she is not ridding the world of all its annoying but ultimately not mean pitfalls and hazards. (She does make it a condition of rendering dragons torchable that they must not eat anyone except trespassing Orthodox wizards.) She is mostly staying at home with her wives and her daughters, reading Rose's books, chattering endlessly with Kanim about all the exciting experiments they'll conduct with the new forms of magic available.
When Jane goes down, Bella has to make sheepish announcements that her resurrection powers turned out to be impermanent; she hopes they will return but can offer no timetable.
Meanwhile, news of one specific resurrection (Howard's) has spread far and wide.
"Yeah, I don't think you should," agrees Carinna. "I get my nails cut before I'm going to make glass things that way, now."
"'Wen and 'Lin mostly do things with metal, not glass. Bella is the mom who does glass. She likes it for magicking."
"We're lucky like that," says Carinna. "Bella said when I asked that technically I'm hers and Sherlock's and technically 'Wen and 'Lin are hers and Tony's, but it doesn't matter, we're all all of theirs and they are moms together."
"Bella did magic to make us," says Carinna. "And Sherlock and Tony are identical twins and they both wanted to marry her. So they did! And now they are all moms together."
Carinna giggles. "If I hadn't come along then Tony couldn't have married Bella. Since there had to be heirs, since Grandma wasn't immortal then."
"Yeah. And Grandpa and all my moms and me and my sisters and Cricket and Kanim and some other people, too. That's some of the extra fancy magic Bella got. She can immortal people."
She pauses at the doorway, peeping out at the strangers.
"Probably in one of the stacked rooms," says Kiawen. "The library or her workshop or something."
"There is the brainphone!" says Carinna. "Then she can just come here. I almost forgot it." And she closes her eyes and tilts her head and summons Bella.