Is this a general Tinycore issue or just dCore?
Probably it is a common tinycore issue,
but i could be that for dcore users it is interesting to interact with other distros, especially deb-distros?
...maybe i'm wrong.
And are you planning to share the /etc/group or other files between distros?
i'm sharing lots of files, also config-files in different distros,
so i have to check the permissions and user- and group-ids all the time.
And do all the other major distros use the same group and user numbers?
i guess the major difference is between deb and rpm-distros.
as far as i know the numbering of new users in rpm- and deb-distros start at a different id.
hopefully the major daemon- and services-groups use common group-ids, but i do not know it.
actually i wanted to suggest that dcore adopt standard-ids from debian.
thank you for your interest.