Congress has resolved this problem. They have allowed a wide variety of religious groups to pray at the opening of a session, including Muslims as far back as 1992. However, the waiting list is quite long and the red tape is fairly onerous.
Multiple benedictions are nonsense, rendering the "come one, come all" concept moot.
They don't have to allow multiple benedictions. All they have to do is, over time, allow different religious groups to open different sessions of the town board meetings.
There is nothing in this article to show that they are not doing that, only that they might not be doing so for every group that believes they should be represented according to said group's timetable.
Of course, the Scientologists are on equal historical footing with the Wiccans so perhaps they could start by allowing a join benediction given by representatives of both.