@tm -
I don't think supporting Ganga or Sanchi is her undoing.
She had doubts about Sanchi and Ganga's feelings for Jagya at about the same time.
Ganga is a nobody for her she is just someone her family has given shelter to.She did feel a certain kinship with Ganga but in no way was she responsible for her welbeing.
She confessed her doubts about Sanchi to Shiv because she is family.There is no reason for Anandi to tell Shiv or anybody in his family about Ganga's feelings for Jagya because Ganga is of no concern for them.
As for supporting Sanchi - she always felt that Jagya Sanchi marriage is a bad idea and tried convincing them when they did not listen to her she just did her bit help Sanchi get acquianted with Haweli and it's way of life so that Sanchi can prepare herself.She did it because Sanchi was family.
Ganga was never ever her responsibility She was Singhs mainly Jagya and DS's responsibility.She was just someone she liked and bonded with her like a girl bonding with another girl.After all she had more in common with Ganga than she had with Sanchi.She never supported Ganga against the family members.She was angry with Sumi for allowing a lone woman with a small child to leave home in the middle of the night.She was not responsible for the way Sumi treated Ganga.When Sanchi behave d badly with Ganga she apologiesed on behalf of Sanchi.
As for her not thinking of Ganga as a possible partner for Jagya it was not her responsibility.It was his family to see someone suitable for Jagya and have her meet the girl.
When she had doubts about Jagya's feelings for Ganga she confronted him and tried to bring this issue to Shiv.But it was Shiv who brushed away her concerns.
She kept quiet about Jagya Ganga issue because that has no role in SaJa break up.
There was never any support for Ganga - Jagya from her despite her liking Ganga and thinking in the end that they are right for each other.
She supported Sanchi and her efforts to change herself.It was Sanchi who did the cheating and will most likely blame her falsely.