Dear respected Rabia Rana,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
I’m sorry you’re having a problem with Formatting changes when you linked link content between two Word documents but based on your description, we can work together to resolve it.
For the situation you encountered, we deeply understand the inconvenience caused and apologize for it.
As per your description, in your scenario better to fix/apply the same style or heading Styles on both your Word document (source and target file) and let Word's TOC handle the rest.
Also, may I know have you tried to use ordinary cross-references (act as hyperlinks).
We appreciate your understanding that sometimes the initial suggestions may not resolve the problem very soon. However, we can work together to narrow down and resolve the situation. So, please kindly provide more information below to let us work further.
1. What’s your Word version? Open Word > File > Account > Production Information and share a screenshot of it. (Please mask your private information.)
- Does the issue happen on all files or a specific one?
Appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely,
Waqas Muhammad