[@AlexanderML]

In lieu of gaining domains, could it be possible to gain portfolios instead? Since Portfolios are part of a domain, gaining a portfolio outside one's own domain implies acquiring a domain, whereas acquiring another portfolio within one's own domain would mean the god has expanded its hold on the domain.

Else in order to be come an elder god you have to have multiple domains, but that would be weird to have a god of multiple things which may or may not be related to each other as domains could be something as weird as "God of the seas" and "God of Space."