Tots bot sell specially designed dolls nappies, complete with wrap & bag
Nappies by mink sell a teeny premie nappy which would work! (they fit Eleanor when born at 4lb 11, but didn't absorb anything!!)
How about you make your own? Maybe a prefold & wrap would be great for her with her own set of washable wipes for 'her baby!'
Or I've got 2 old tots bots size 1 aplix nappies with I've got listed in the treeshare ffp! They are balding in places, would esme like them?