Tosafos (to Suka 28, Sanhedrin 86, and M'nachos 61; and Tos'fos Harosh to Sanhedrin 86) cite various verses containing the words "בני ישראל", b'ne Yisrael. In some cases, they note, the g'mara seeks an additional d'rasha to include converts into the halacha that the verse assigns explicitly to b'ne Yisrael. In others, the g'mara does not seek any such additional d'rasha. They ask this as a contradiction: if such a d'rasha is necessary, why is it not necessary everywhere?
They reply (in all three places, as do the Tos'fos Harosh in Sanhedrin) that "maybe" there is some such d'rasha that the g'mara does not mention.
Does anyone (1) know of a stronger version of that answer, one that either (a) explains why such a d'rasha would be mentioned explicitly in some cases and not in others or (b) lists such d'rashos that the g'mara does not, or at the very least (c) claims the existence of such d'rashos without qualifying that claim with "maybe"; or (2) know of another answer to Tosafos' question?