A bit of explanation first: we have an Exchange organization across multiple sites (regions) but only one forest. These "regions" are US, Japan, Europe, etc. and each region has its own Exchange servers to manage. Furthermore, we have a single common Office 365 tenant and already configured hybrid environment. This was configured and ran in Japan.
That region configured the hybrid with their own settings (Edge Transport Servers), Transport Certificate server (and certificate), organization FQDN (which configures outbound mail connector), etc. Of course, the migration endpoint is now configured between O365 and Japan and so is mail flow.
Now, we would like to configure a hybrid for Europe as well. So, adding new domains, but would like to set Europe's Exchange servers for mail flow, no Edge servers, Europe endpoint, etc.
So, if we run the hybrid on Europe Exchange server and choose only Europe specific configuration and settings, what will happen to the existing hybrid configuration for Japan? Will it be overwritten or will it stay the same and the new for Europe will be added?