(9) In his Responsa R”y Mintz rules that even if its wings and legs are removed, it is still considered whole. The reason the Rema didn’t say that even if it is missing its wings, is because in that case it would have to be measured for the sixty ratio. The Rema brought parameters where the bird would not have to be measured for the sixty ratio. If the bird was stuffed with meat and vegetables and the like, they too combine to form sixty. This is because the issues regarding something attached are simply stringencies, it seems that a goose lacking its skin will still have sixty against its heart.
(10) There are two reasons that we are more strict regarding an item that is attached. A) The piece it is attached to will absorb more from it than other items in the pot. B) We fear that this piece may have been outside of the liquid, in which case there would not have been sixty against the heart and then became nveilah. However we only say this rule in the case of something biblically forbidden. Regarding something that is rabbinically forbidden, we rule more leniently. A bird that was stuffed with eggs, salted, and it is then discovered that the heart is still in the chicken is subject to the following rule: if the heart is not attached, the eggs cause the bird to be considered as if cooked and combine to form the required sixty. If there is sixty, everything is permitted. If the heart was still attached, the eggs do not count, and sixty is needed from the bird alone, in order to permit everything.