1. No. After adoption, the adopted child will inherit the properties of his/her adoptive father and ot biological father,
2. You won't have to file any suit against her for any declaration,
3. You should contest the case filed by her claiming her share in her biological father's property duly submitting the evidence that she was adopted by someone else and that she has claimed her share from her adoptive father also admitting that she was adopted by her adoptive father,
4. She does not get any share of your grandfather's property for which the question of her releasing her share does not arise at all,
5. The properties of your grandfather will now be equally shared by all his legal heirs.