[This is physically possible, and is called superfetation.
Its last recorded occurrence was in 2009 by a couple in Arkansas who became pregnant with a second child several weeks after her first pregnancy.] b) The intercourse of the second husband may injure the child through pressing too much on him.
A second marriage following the death of one's spouse poses other challenges.
One may wrestle with various emotions when contemplating remarriage.
There are those who regard remarrying as an act of betrayal.
But if loyalty means maintaining whatever was built in the first marriage, it is entirely likely that the surviving partner can more successfully accomplish this with an understanding new partner.
In a perfect world, men and women would marry, live long and happy lives together and leave this world at about the same time. And too many marriages simply do not last and collapse into divorce.