But I was just thinking. If they ARE being subtle. Lord Umber never actually pledged fealty to Ramsay and House Bolton at all. He specifically said he wouldn't bend the knee and just gave him RickonGift. Ramsay probably isn't stupid enough to flay the last known male heir of the Stark line. Since Sansa was mentioned (in the show again we know its critical in the books) as being critical to securing their control of the North. Rickon must also be somehow.
So, technically, Lord Umber never changed allegiance to House Bolton and it wouldn't be betrayal when he fucks him over... If they want to go that route that would be cool.