some questions for online adding new data nodes for over hundreds PB data (no replies)

Dear MySQL Cluster pioneers:

According to the official documents of :
1, https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-nodes-groups.html
2, https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-online-add-node.html

I have some questions for online adding new data nodes for over hundreds PB data:

I, how many nodegroups should be created in a 1 replica cluster when adding 2 data nodes or 4 data nodes ? since replica is 1, so one should create 2 nodegoups for 2 data nodes and 4 nodegroups for 4 data nodes, am I right?

II, if just adding new data nodes and without changing other datanode settings, such as not changing "1 replica", according to https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-online-add-node-basics.html , could one skip the 7th and 8th steps to not reorganize the old existing tables and data, to let the old tables and its old-and-new data to stay on the old computers, but let the latter creating tables and its new data only to spread to new computers?
In a word, is it work stably to only follow the before 6 steps to add a new nodegroup with regorganize the old tables?