I've done this before. The gate staff have no idea who the bags really belong to, so if she says they're all hers then they're all hers, even if one is yours. Provided of course that all your collective bags fit within her cabin and status allowance - if you need to use some of your allowance then I'd expect you'd have to be there. If you all check in online anyway the night before then you'll be able waltz straight through the F wing into security without stopping