Unfortunately this is not available from the specific reservations neither.
I reported this bug to Airbnb months ago but it hasn't been fixed yet.
Last update I received was they're still having difficulties solving the issue but they're working on it.
In the meantime, I asked the main host to request money on my behalf but this is definitely not the best solution. Can be akward as a guest to get a money request from someone you never talked to.
Not very encouraging to use the co-hosting system properly in such conditions...