Add tests for 3 dynamic merges to verify dynamic data types dependencies lead to complete definitions

Problem/Motivation

In 🐛 Merging data types leads to incomplete definition Fixed
tests for 2 dynamic typed things was added.

We can increase our confidence and have more complete test coverage for the "many" (more than 2) test case.

This is not in the other issue because this is a complex problem to think about and doesn't need to block the bug fix and good test addition for the 2 case.

Proposed resolution

Remaining tasks

Think about what 3 dynamic levels would look like.
thing1 -> extend2 -> extend3
or ...

thing1 -> extend2
                               -> merge
thing3

User interface changes

NA

API changes

?

Data model changes

?