Cookie Domain - Tracking separate site subdomain

I have two sites:

I need to track as a completely independent site and see hits from as refferal

The cookies set by GA4 and GoogleAds must only apply to the domain (and any sublevels:

Cookies should be managed by the server.
Currently in the GA4di ssGTM client I have the setting active:
“Migrate from JavaScript Managed Client-ID”

How should I set the cookie domain and flag?
1] for clientGTM GA4 setting tag?
2] for ssGTM “GA4 Client”?
3] for ssGTM “Linker Conversions”?
4] In the GA4 Admin panel, how should I configure the domains at the “Data Stream” level (Include only domains…)

Thank you