The WI Constitution says assembly at the seat of government. But that still begs the question of what parliamentarian rules they abide by.
I did find this little tidbit.
Each house shall be the judge of the elections, returns and qualifications of its own members; and a majority of each shall constitute a quorum to do business, but a smaller number may adjourn from day to day, and may compel the attendance of absent members in such manner and under such penalties as each house may provide.
I wonder if evenly dividing between them the money their fleeing has cost the taxpayer would be an appropriate penalty? Seems only fair...