Hey,
It sounds like something that should be doable!
A suggestion might be to extend the subpanel functionality, and add a Custom button to the Subpanel?
This’ll allow you to have a button on the subpanel that performs your custom code, (in this case, Check for a value, then do/don’t redirect)
I’ve found a few short guides around this, hopefully they’ll be a good place to start:
https://www.youtube.com/watch?v=j2LuRaSGU2M&feature=youtu.be
https://www.youtube.com/watch?v=96oM9VEQ7mQ
https://community.suitecrm.com/t/how-to-add-a-custom-top-button-to-any-subpanel/32267
https://community.suitecrm.com/t/add-a-custom-action-to-the-buttons-on-the-right-of-a-subpanel-row/36894/2
Unless any other user can think of another solution?
Let us know if you’ve got any questions or issues!