Hi! I have carefully undergone your problem & what I would like to advice you is-
1) The abdominal pain
is common after such intervention in pregnancy
which seems complicated
2) In such situation where the pregnancy is complicated in two important aspects, twins & one of the fetuses having congenital brain defects, it would always be better to consider termination of the pregnancy in view of future harm to the mother as well as to one of the fetuses, if at all the pregnancy be carried on.
3) It has been a general natural rule that any defective carriage is going to be terminated ia a natural way!
Thanks & wishing a smooth & uneventful pregnancy to your daughter in law!