Responsa for Ketubot 98:16

Q. A was survived by his wife, a married daughter, and a single daughter. Subsequently the married daughter died and then her death was followed by that of her mother. The latter had not taken the required oath regarding her ketubah. The unmarried daughter took possession of A's entire estate; but, A's son-in-law demanded half of the estate on the grounds that his wife had been entitled to it, and that he was her rightful heir.
A. As long as A's widow did not take an oath regarding her ketubah, A's entire estate belonged to his two daughters. A's son-in-law, being his wife's rightful heir, is, therefore, entitled to half of A's estate.
This Responsum was addressed to Rabbi Menahem.
SOURCES: L. 226; Mord. Sheb. 780. Cf. Israel Bruno, Responsa 21.

Q. A has two sons and several daughters, some under six years of age, and some older. These children possess property of their own which they received as gifts. Must A nevertheless provide them with food and sustenance? Your pupil is inclined to think that A is under no obligation to do so, since feeding one's children is considered by the Talmud to be a charitable act (Ket. 50a), and A's children need no charity.
A. Your reasoning is correct as far as the older children are concerned, but does not apply to those under six years of age, for as the Rabbis decreed that a husband must provide his wife with food and sustenance even if she has property of her own, they also decreed that a father feed his children until they reach the age of six, even though they have property of their own.
The query was sent by Rabbi Asher.
SOURCES: Am II, 242, 244; cf. Asheri Ket. 14; Tur Eben Haezer. 71.

Q. A mother demanded support from her three sons. One son has no money except his salary as teacher. The second son possesses fourteen marks. The third son is rich but does not live in the same town. Who must support the mother?
A. It is the accepted law that children are obligated to support their widowed mother only out of the possessions they inherited from their father, but not out of their own possessions. However, children of means may be forced to support their mother as an act of charity [since a Jew may be forced to give charity to the poor]. Therefore, any son who would himself be thrown upon charity were he forced to support his mother, can not be forced to do so. But those sons who have means should support their mother in proportion to their wealth. These sons, however, cannot be forced to support their mother out of their own money, but can do so out of the money they are usually obliged to give to charity, although they would thus incur the curse of the Rabbis who say: "Cursed be he who feeds his father out of the poor man's tithe" Kid. 32a.
SOURCES: Cr. 198; Pr. 541; Tesh. Maim. to Shoftim, 15; Mordecai Hagadol, p. 197d.