One question she always has in the back of her mind "Will he or will he not leave his 'wife' for her"?
Her every move against anika will eventually bring ShivIka closer. Why?
Shivaay hated Anika because of the ONS MU. Anika hated him for what he did to her inorder to get married. It's upto her if she wants yo forgive him for that or not BUT whatever Tia will say or do, it will have no effect on Anika as she knows Tia's true colours.
Shivaay is sympathetic towards Tia because he feels she got kidnapped because of him other than the doesn't have any relation , neither physical nor emotion with Tia.
Before things were different for Tia and a lot easier I bet. Anika is not an ordinary girl for Shivaay. After the kidnapping track he's going to be more cautious of things around Anika. He is in the middle of re building that TRUST which was broken because of that MU according to Shivaay. To be trusted is a greater compliment than being loved. These are the primary qualities that attracted them.
Tia is going to get caught in her own web.
I feel she will unknowingly bring ShivIka more closer by her so called tricks against them.