A stack of django sites that match 90%. Best practics?

Question

Django

There is a task to make a stack of sites that are 90% identical in functionality, but with differences in display and structure. Then all these sites need to be developed in parallel, and the improvements on the sites will coincide by 3/4.
Making many base apps and inheriting from them is not an option, so the structure can change and not predict the range of changes in advance.
As an option, make 1 main site, and transfer changes to other sites through meld with the necessary variations.
We need an idea how to maintain such a zoo from similar sites with the least losses.

Answer 1

If 90% of the code is shared, then the most reasonable option is to have a common codebase.