Welcome! This forum has a treasure trove of great info – Scouters helping Scouters! Just a heads up, though - all content, information, and opinions shared on this forum are those of the author, not the BSA.
Not necessarily. The connection in my.scouting just needs to be made by council personnel.
Contact your local council and ask them to use the Registrar Tools to look up the children. When they look up the children, they want to check children’s “User Relationship” and make sure that children are connected to the parent(s) with only the correct BSA member ID number.
ETA: They may need to reach out to the previous council to get the connection made. I’m not entirely sure since this is an inter-council move. The SUAC folks can probably clarify that bit.
It’s possible that she might have the relationship set up already in the former council. If that’s the case, she should log in at my.scouting and set her old BSA member ID number as primary (using Manage Member ID).
Note: She should set her BSA member ID number back to the current council before logging back in to Scoutbook, or she might create a new Scoutbook account.