There may well be some extra seats at Knotts. The 'Chama' wasn't always a bastardized combine. When they began service at Knotts in 1952 the car was intact with full parlor car accoutrements. She remained that way till the late '50s(?). Bottom line is that Knotts took out the seats and may still have them. Thank God they seldom throw anything away!
I remember going to Knotts in '54 when my grandparents were out for a visit. Grampa was a retired Rio Grande conductor with a lifetime pass. The Ghost Town and Calico honored pass holders from the D&RGW with free rides (back in the days before fences and blanket admissions when you bought a ticket for each attraction).
Roy Boucher, former Superintendent of the RGS and one of the fellas from back there who helped Knotts set up their railroad, was conducting that day and when he saw Grampa's pass he said, "Come with me." A coach key was produced, the 'Chama' opened up, and we rode in grand style in those plush seats, right behind the 340 ('40' back then). I think we did a couple of trips around the park while my ol' boomer grandfather and the former Super' talked railroad.
Great memories and solid imprints on the mind of a budding 9-year-old railfan. No wonder Knott's little empire is such a turn on for me!