Pre-assigned breakout rooms(500 participants plus).Limits to adding late registrants after launch?

[BT2021]

The scenario is as follows:

*** A Zoom meeting, expected to have more than 500 participants, and breakout rooms used. (Note that a Zoom large-meeting expansion will be taken).

*** Pre-assignment to breakout rooms will be done beforehand (loading pre-assignment csv via Zoom web-portal), relying on email addresses of registrants (taken from the registration report).

*** Planned number of breakout rooms is 16 to 32 rooms.

*** HOWEVER, we expect late registrants, even after the Zoom meeting has been launched, and we wish to accommodate them.

*** The plan is to rely on the pre-assigned breakout rooms, and then, for the late registrants we plan to  perform manual assignment during the meeting (to those same rooms).

*** The meeting starts with a plenary section (before breakout rooms are opened), during which much of the late-registrants could be assigned to breakout rooms. The plan was to do that  within the Zoom-app (desktop app / Windows).

BUT the following questions and concerns arise:

*** Considering the section "Limitations of meeting breakout rooms" from support article

 https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0062540   

"Up to 100 breakout rooms and up to 1000 participants can be pre-assigned to breakout rooms."

*QUESTION 1. Under the scenario described above (pre-assigned breakout rooms, but during the meeting also adding late registrants to those breakout rooms), what behaviour can be expected from Zoom (assuming if we have more than 500 participants? Will the other limitations described in KB0062540 allow assignment of participants if we exceed the other limits indicated in the article?
*QUESTION 2. If changes to the pre-assigned rooms are made via the web portal, AFTER launching the Zoom meeting (but before opening the breakout rooms), will Zoom be able to use those changed pre-assigned rooms? 

[BT2021]

Answer to Question 2. I did do a test regarding Question 2. The behaviour is as follows: Zoom uses the the pre-assignments as they were when the meeting was launched. So updating the pre-assignments after launching the meeting has no effect, unless the meeting is relaunched.