What you are asking is bringing organisation's cultural change. For this you need to train your managers on teamwork.
In the course of my training activities, occasionally I find my participants lamenting for lack of teamwork at the top level. Most of the times, the training programmes are attended by junior level or middle level participants. Nevertheless, at times juniors are caught in the crossfire between heads of the departments. In a very prominent IT companies of India, two board members were not seeing eye to eye.
To tide over this problem, I strongly recommend you training your senior management professionals on "Understanding and Overcoming Team Dysfunctions". Click on the hyperlink to know the details of the training.
This training is free from games. Games as a tool of training is works best at lower level and not necessarily higher level. The dysfunctions are nothing but diseases of the organisation. Senior managers need to make comprehensive plan on how to eradicate the diseases.
In addition to this, the senior managers also need training on "Conflict Management Skills". In this training, how to remove negative conflict by substituting positive conflict in its place is taught. Far from removing, understanding difference between positive and negative conflict itself is achievement. Not many senior managers know this.
Earlier, I have given my comments on conflict between two senior employees. Click the following link to refer the comments:
If you wish to hire my training services then feel free to contact me.