Diadem: no more Alliances

Hello,
yesterday, me and some guys have organized a try to complete the Emergency Mission on Diadem. Although we had somehow arranged to be a full Alliance, and the Duty’s description confirmed the possibility of entering by Workshop up to 24 people, we didn’t find any option in the Party Finder to organize this Alliance and enter all together in the same instance.
We had to split up in the three parties, and enter one by one in duty, hoping to find ourselves all in the same instance, which unfortunately didn't happen immediately. And up to that, besides not being able to enter together, there was the problem of the waiting time of 30 minutes between one exploratory mission and another, making things very slow and complicated.
We did, then, some research on the web, and it came out that once was possible to get in as pre-made Alliance... is it something that's been long since canceled?
Because at the current state, and given the very low population of players in Diadem, it’s impossible to close the Emergency Mission, even managing to put together 72 people to do it.

Well 5.1 will introduce some Ishgard rebuilding thing.
They said they'll be using a lot of Diadem mats crafters will need. So hopefully the population goes back up.