I have good news to report!!!
Another mother sent an email to the relevant teachers and administrators, asking what happened to the math acceleration plan that we all discussed right before school started. Further emails ensued (including from me; I guess I cannot resist). And it looks like indeed the kids will be accelerated two grades in math, along with any gap-filling that is deemed necessary after administration of the next grade's year end test. Things were not quite set yet (they have never tried this particular arrangement before) but the test will be given this week so they can get started. Their classroom teacher is fully on board and they will be getting the 5th grade curriculum from the gifted specialist during pull-outs and in a small group in the classroom on the days they are not pulled out. The school has also purchased accounts for them to do the Stanford online program as another tool sometimes.
So...things are looking up! We have a meeting this Friday to pin down specifics. And most importantly, the teacher spoke w/ my kids about this plan yesterday and they were SO happy and excited to tell us about it. They had a pediatrician appt this morning and one of them also excitedly told her about it.
Thanks everyone for the advice. The classroom teacher already purchased Developing Math Talent by Susan Assouline after I mentioned it...