Make the Product Owner a part of your Scrum Team. Why? Because it’s supposed to be one delivery unit. Not two, with one side delivering ideas, and the other side delivering the product and then both sides arguing about what was really required. I’ve seen a good share of political fights for power over people being carried out on the back of the employees: The PO wasn’t allowed to sit next to the Dev Teams because the PO’s manager was afraid of limited influence. Of course his behavior consequently influenced nothing but lead time and the quality of features.
The Product Owner, just like the ScrumMaster, also assumes a leadership role. Therefore, empower your Product Owners to make (risky) decisions on their own. Why? Because eventually it enables everyone to learn from mistakes: A Product Owner once hesitated to switch on a feature that went live four weeks ahead of schedule, because her superior was on vacation and she was afraid that something might go broke. So instead, all the additional buffer that could have been used to fix potential bugs before the promised date, was consumed and the feature was switched on the exact date when it was supposed to – and, of course, it turned out to be buggy and left behind dissatisfied customers.
If your Product Owners work in a different location than your development teams, make them visit each other on a regular basis. Having Skype calls and telcos is better than writing emails and tickets, yet, looking each other in the eye when trying to fix a serious issue or discussing priorities is a whole new ball game! Especially regarding different cultural backgrounds and mother tongue, personal meetings and workshops help to identify barriers quicker and to get the involved parties on the same page. If you encounter political differences between parties, set up a meeting on neutral ground so no one feels like they’re having a disadvantage.