How to compare different user research resources and findings?

I would like to create my own persona(s) for my research. While due to some limitations, I don't do any formal user interview or observations myself. What I have as resources are the user research which have been done by another research team in the company. I have currently four different sources of user research materials. Mostly, they did user interviews and observations. they also did usability testing for one particular product following certain kind of scenario.

My objective of this research is to identify the users' expectations, their pain points and their common points.

Could you give me some advice about how can I use the existing research?

*The existing research focused on the similar user types with mine. Therefore, I think that I could reuse their raw data to re-analyse and construct my persona(s)