Mine are looking for a treat most of the time when they come in and usually get one they are very spoiled. Sounds like yours are too. Love your avatar.
Some of mine will come in the back door too but my floors all old wood so I don't mind I just clean up and they usually don't go far once in.. You maybe able to shew them out enough times they begin to get the message.
I don't have a pond for my flock of 9 Muscovy's and 4 geese they have kiddy pools and love them, yours will too just go buy one before they put them away for the summer.