Je was op zoek naar: sneak (Engels - Wels)

there is no way that this kind of development should sneak in through the back door
yn sicr ni ddylai'r math hwn o ddatblygiad sleifio i mewn drwy ddrws y cefn

there is no point in trying to sneak in these little issues when your previous remarks displayed a genuine interest
nid oes pwynt ceisio codi'r materion bach hyn ar ôl ichi ddangos diddordeb gwirioneddol drwy eich sylwadau blaenorol