If the first son (that opens the womb) dies at day 3 (and therefore was not viable), and then there were mutliple sons over the years, when the father dies does the oldest living son get the double portion?
Barry Epstein, Dallas, USA
The rule is that as long as a child was born (even if he was only alive after sticking most of his head out) after nine months, the child that comes after him cannot be a Bechor regarding the double portion of inheritance. If the child was born before nine months and there did not seem to be anything wrong with him, and he did not live more than a few days, the child born after him is not a Bechor, as it is unclear whether or not the child was a Nefel (see Aruch Hashulchan C.M. 277:5 at length on this topic).