Hi James,
The Linked manger functionality of the docking manager can be used to achieve that. Please take a look at this attached sample.
You can also take a look at this sample for more information on linked managers. C:\Program Files\Syncfusion\Essential Suite\2.1.0.9\Tools\samples\Docking Package\LinkedManagers.
Please let me know if you have any questions.
Thanks
Vijay
MDILinkedManager_8043.zip