Can Second Opinion be obtained at Mayo if starting 2nd round of chemo?

I'm trying to get information for my sister regarding Second Opinions. She is currently in treatment for Invasive Ductal Carcinoma (HER 2+), with it spreading to her lymph node near her arm pit. She has gone through chemo/targeted therapy last Fall (Sept-Jan), she had a double mastectomy with 3 lymph nodes removed in Feb 2024. After surgery found out she still had active cancer cells, so she has started second round of chemo (which is supposed to last until beginning of Dec 2024). Also today (4/10) they have her starting radiation as well for the next 5 weeks. Back in Aug, I had initially talked to someone at Mayo and they said if she is in the middle of treatment she couldn't come for a second opinion. But now that she has gone through all these treatments and has questions going forward can she get a second opinion, just to make sure this course of treatment is the best course of action? She has lots of questions, but not getting all the answers like she originally was from her current doctor. Please help!