I believe that I addresssed a similar question before. It is gratifying that your daughter cares, but she has no right to demand marital counseling and if done as a result of cohersion -has little chance for success. It is fine to make the suggestion, but you have to keave it it there-no threats or force, etc. Best wishes and good luck You can set up some ground rules re: yelling, screaming and verbal or physical abuse.
I agree that it could help. But it should be by agreement not by force. In addition do not expect the result of family therapy to be miraculous.