<p>can two use cases extend  or include each other at the same time?
 A extend/include B  and B extend/include A</p>

I'm pretty sure the answer is "NO".
You've just described the digital equivalent fo the chicken and egg problem.
Circular references are [almost] always Bad Things (tm). The only place I know it to not be horrible is in the context of a linked list, in which each entry has a pointer to another of its own type.