Regarding Migo

Are there any rules when using a migo as a claim or a migo of loyalty? Because I have seen many disputes in the Rishonim, for example, in the question of the Tosafot in Rish Baba Metzia, why didn't they say that a fiduciary is a fiduciary in the division of my migo, so that he claims it is all mine? And there are many excuses in the Rishonim. And I have seen that those who answer that it is from a migo of greed believe that a migo is a matter of loyalty because from a claim point of view, there is no problem with greed. And indeed, those who answer that it is from a migo of wealth upon wealth, this only works out if we say that the issue of a migo is a claim point of view. And if so, it is difficult for the Gemara in Rabbi Chiya Kameita to rule out a migo because of greed. Then it is proven that a migo is a matter of loyalty. Unless the Rabbi tells me that the question regarding a migo, whether it is a claim point of view or greed, is a question in each individual case, and if this is really so, please explain why each case would be different.