Does anyone know if there any One Piece photo shoots happening at the MCM in May? My sis is going as Perona in a gown and wants photos with other one piece cosplayers

I'm sure there will be! There always is maybe check out the MCM Expo forums? There's most likely a thread for it already!

There doesn't seem to be a One Piece cosplay thread over at the MCM forums yet, but I'm sure there will be one organising a meet of some sort nearer the time.

I may well be going as Nami (Arlomg Arc post-stabbing) on one of the days.

I'll be going as time skip nami, your best bet is to ask on the Expo facebook page

http://www.facebook.com/groups/35517615269/10151398285685270/?ref=notif&notif_t=group_activity