My girl is quite a heavy wetter too and i notice the Baby Love nappies become pretty bunched up if i leave it too long between changes and they're pretty full. Maybe try changing him a little more frequently and see if that helps??
Isnt it awful when the poo comes out the back!!
Thanks Reet, yes I think its the wee pulling it down. Glad i'm not the only one who's suffered a pooey backed baby!