Your husband should have cancelled the seat trade saying to the large lady:
He thought he was getting three bulkhead seats but only got two,
He wanted to sit with his famly,
Her occupying part of his seat was not acceptable.
The choice of staying put but lowering only the arm rest in question and squeezing the other way against her companion.
Travel tips:
http://members.aol.com/ajaynejr/travel.htm
[This message has been edited by AllanJ (edited Dec 25, 2003).]