Connect Multiple Dates to a single one (Master Calendar?)

[arci93]

Dear everybody,

I stumbled upon a situation where I have 18 different "installment date" fields in a single "Invoice Table".
(e.g. i have Payment Date 1, Payment Date 2, …, Payment Date 18)

I want to create a single dimension called "Expiration Date" so that, when I filter it, i can check all the payments expiring on a certain date.

I was wondering how could I achieve something like that? What is the bests practice in this case?

Thanks in advance and best regards,
Alessandro