Abhi is firm on custody drama as the condition associated to that is something which is important to him. He does not care whom abhir will choose but he only wanted abhir to know the truth that abhi is his father and akshu can not full fill her promise made to abhir i.e telling abhir his father's name, if he does not win custody.
So he will win custody and give abhir to sharma fam after telling him he is his real father. This will make akshu realize that she messed up a big time. She took away the rights of that person who always fought for her right with the whole world.
1. When maya used akshu's voice and ppl started calling akshu as maya's duplicate abhi is the one who fought for her rights.
2. When arohi was humiliating akshu infront everyone abhi was the one who took stand for her.
3. When papa birla was humiliating her he is the one who took stand for her.
She just took away his rights and served it to some one just because she thought abhi never wanted a kid will hit her big time.
Abhinav will realize whole truth in custody drama. He will realize why abhi did not picked up the phone that day. Muskaan track was added to make him realize how possessive a brother can be for their sibling.
So now when he hear manjari saying if they would have waited for 10 minutes my son would be alive, roohi would have her father. That might make him understand abhi's pov too.
That's when he will realize nobody was wrong the situation was wrong. By looking at the precap they might be repeating abhi humming lag ja gale for akshu. That's when they slowly start showing how abhira belongs with each other as manjari has already told them upfront and now they will start noticing this too. It's goenkas time to realize abhira never moved on.
Note: this is just an assumption.