Pausing and resuming at dag runs

[swarnadeepC]

We have a use case where we are setting a property in our product. All the dag runs after the property is set should be paused and the already running dag runs , should be allowed to run to completion. Can someone please suggestion some way for this?
Another approach i can think was set the default pool to 0 (which will be used for dag runs submitted by default), identify the already running dag runs and if there is any way to change the pool for already running dag runs/tasks . Bt not sure if we can change the task pool dynamically