Currently you can only single click individual pupils to add to pupil portal or select them all.
iSAMS should add normal filters (e.g. Year Group) on the "Create Pupil Users (from Pupil records)" within Control Panel. This would allow schools more control over who needs a student portal account.
This was added in 2020, it's now 2025, can't believe this simple addition hasn't been implemented. If you want schools to pick your portal, make it easier.