samba - Feb 2022 - Joining member server

I have three DC's - one running Louis's packages (4.15.3 on Ubuntu
20.04) and two others on 18.04 running the distro packages (4.7.6).
?
I'm joining a member file server running Louis' packages 4.15.3 - and
want to make sure that joining using samba-tool is fine.
Recap: 2 or the 3 DC are running a mixture of 4.7.6 and 4.15.0+, but the file
server being joined as a member is running > 4.15.0.
?
I assume it's ok since the machine running samba-tool is >4.15, but I
also don't want to whack my AD back-end etc.
?
TIA
-Greg ?

Perhaps I should have been more clear/explicit.
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The Wiki says that you should ONLY use "samba-tool" to join a member
server IF the samba version is >4.15.0.
(https://wiki.samba.org/index.php/Setting_up_Samba_as_a_Domain_Member#Joining_the_Domain)
?
Obviously in this case, we have mixed versions.
But the machine being joined is running a samba version >4.15.0.
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Again, I'm like 95% sure this is fine, but asking now can save many hours
trying to recover whacked DCs, so here I am.
?
?
> I have three DC's - one running Louis's packages (4.15.3 on Ubuntu
20.04) and two others on 18.04 running the distro packages (4.7.6).
> ?
> I'm joining a member file server running Louis' packages 4.15.3 -
and want to make sure that joining using samba-tool is fine.
> Recap: 2 or the 3 DC are running a mixture of 4.7.6 and 4.15.0+, but the
file server being joined as a member is running > 4.15.0.
> ?
> I assume it's ok since the machine running samba-tool is >4.15, but
I also don't want to whack my AD back-end etc.
> ?
> TIA
> -Greg ?