回复：婆婆拒签，请有办法给个主意

Understand your situation. Take your parents or in-laws to travel when you have chance, make them happy daily.

For the letter to the Visa officer, it could be a one page letter:

1) Enhance the strong tie your mother-in-law has in china, e.g. other children and grandchildren

2) your finacial capability: support her living and bording, medical....your salary, company, ...

3) Purpose she comes, visiting....

Make the letter fun and sincere.

Good luck!