observed dataloss while replacing zookeeper severs (zookeeper 3.5.0)

Hi,

I am experimenting with zookeeper server node replacement using 3.5.0
version.
In my setup I have 3 zookeeper servers forming a quorum and want to replace
all 3 zookeeper servers with brand new instances of servers.

If I replace all 3 nodes in quick succession (using reconfig -remove x -add
y).
Is there a possibility zookeeper data may not be resynced completely on
the new instances of zookeeper servers due to quick succession. As I
observed that some data nodes (znodes) are not present in the zookeeper
database after replacing all members in the quorum.

Is there any way I can avoid this and how should I ensure data has been
resynced before proceeding for next server replacement.

Appreciate you help.

Thanks Regards,
Deepak