Own and Open up

Own verb - To keep, control, or experience as one's own.

Open up and own are semantically related In some cases you can use "Open up" instead a verb "Own".

Open up verb - Cause to open or to become open.

Own and open up are semantically related in declare topic. Sometimes you can use "Own" instead a verb "Open up", if it concerns topics such as confess, admit truth or reality of something.