Valco Twin Runnabout adding 3rd child

[craftysierra]

I know I can add the toddler seat, but do any of the standing boards fit? Trying to decide what will work for #3 on the way. My kids will be a little over 3 and 17 months when the baby arrives.

I seem to remember seeing in the past a board to stand on that also had a seat would something like that fit? I have a twin valco from 2005.

Thanks
Sierra