I see what you are saying. The category is set up incorrectly and the wording on the profiles is confusing. The proflle is a 1600s one so it would belong to the historic Penobscot. We use tribe in the name only as the title of subprojects or if it is in the official name. Then the descendants' profiles state that she was a member of the Penobscot Nation of Maine which didn't exist yet. When the categories are set up correctly they explain which profiles belong to the category. The categories that are Federally Recognized tribal categories are for registered members of the actual tribe.
Descendants who are not tribe members have a category - self identified Cherokee, for example, but that is a modern day thing. Mostly living people use that category.
So to answer your question, anyone can descend from a tribe but only tribe members belong to the tribe and that is what the category is for.
We can make a descended from category if needed. Members of tribe categories share the different aspects of tribal identity including language, culture etc.
I will see if I can correct the categories and make one for descendants. Thanks for pointing this out.