Have I chosen the right analysis?

I am analysing changes that happened in a merger. It is an archival study utilizing survey data. I have a set of 9 survey items (5 pt scale) that I am tracking from pre-merger to post-merger.

I chose a Two-way Between-Groups ANOVA but I have some concerns. The biggest of which is the violation of Independence. It's an applied study, so there was certainly no random assignment of participants.

Is this the appropriate analysis, and if so, can anyone point me to some literature that can help me defend my decision?

Any input is greatly appreciated.