Working together with the current Divine Church never crossed his mind. The plan was to use Dinael to obtain the location for her worlds, her three worlds. Then he would start from there, taking them one by one and putting Dinael as the new leader of the Divine Church. There was no working together, he would never ever believe them again.
They broke the truce so easily. An oath that he believed was unbreakable also could not be trusted. The oath was way worse than the contract. He could find out when they broke the oath, but that was not the case for written agreement or contract.
"Are you your father's only child?" Tang Shaoyang asked again. And yes, he was trying to make Dinael turn on her father. He needed her as the head of the Divine Church.