I logged ER on this operation. 9139441
Answer was that it is very good idea.
I dont know if you can "vote" on it anyway hope it helps in to the future.
You can open attached prt , simulate whole group and pretend that it is "one" operation.
Because bottom up now is a constant value and dont consider critical hights - what could be good have.
Probably it could be done by reversing cutting levels or variable step up distance of bottom up option.
we are working on this feature and it can already be tested in our EAP (Early Adopter Program). Additionally we are planning a test with a wider audience during the time frame of the N12.0.2 release.
So you don't have to vote on this, because it is already in the making :-)
Bottom Up Cutting is currently in development for Adaptive Milling and it can be tested in our EAP program.
It will not be ready for the NX12.0.2 release, but we are targeting the release after.