With enough money, anything can be accomplished! That said, adding the
2005 - on 'Plus One' seat wouldn't work, as there are anchors in the
floor that would need to be added, and the seat belt is integrated
into the roof. Can't see how that could be retrofitted. As far as
sliding the middle seats together, I thought that could be done and I
suspect your owner's manual would tell you that. But there would still
only be 2 belts.

The Plus One seat is probably the greatest innovations since the
disappearing third seat, especially as it stows below the floors so
you always have it with you. It was one of the major reasons we bought
the Odyssey over a Sienna.

Dan D
'07 Ody EX
Central NJ USA