So keep the legislature in session. That doesn't explain why legislators who aren't even in the state, let along attending the session, are getting paid a per diem.
I don't know how state gov (or privileged politicians) work, but in fed.gov you only get per diem reimbursement after the trip, and after you have submitted a travel voucher with receipts. And you can't travel in the first place without travel orders.
If this isn't official travel, which these dems seem to not only admit, but flaunt, they should be getting zero dollars.