there were 3 different meanings. The last one doesn't count, but the other two are as follows;
1. A plan;
a combination of various things into one view, design or purpose;
2. A project;
We don't know which scheme JA meant.
I for one am going for the first one, because the second one also includes selfishness at the expense of others, if we ignore Mrs. Bennet in this case ;-)
Charlotte is definitely not harming anyone.
Sometimes I have wondered if it's Elizabeth's ego that suffers here resulting in this harsh criticism.
After all to have rejected someone who is unacceptable to her, but is acceptable to her friend, must make her feel...(err I don't know how to put it - maybe these are not the right words) - less triumphant??