How to re-use an existing relationship?

[madmat]

Hi Folks,

I hope I can put that in an understandable way:

Meetings:
Can be related to all other modules by default, using the dropdown.
I´d like to be able to relate a meeting to 2 modules, Projects (via default dropdown) & Accounts (via a new relation).

Approach 1 would be to use the "Relations" in studio, adding a one-to-may relation to accounts->meetings, done.

But there already is a one-to-many relation in the Accounts module, so there´s no need for adding it again, right?
What would be the correct approach to re-use that existing relationship, so I´d have a select field in the Meetings EditView for Accounts and the meetings go straight to the "Activities" subpanel in the Accounts DetailView?

I´ve tried a couple of ways to achieve this - no luck so far...