I understand that. As indicated in the bolded “multi-diocese”, the Baltimore Archdiocese (as well as others) has participated in the Washington Archdiocese’s rallies prior.
https://catholicreview.org/archdiocese-of-baltimore-has-presence-at-march-for-life/
There’s difference between “multi-diocese” and “multi-archdiocese”.
That’s my point.