I hope you need to adjust leave balance of employees against Encashment like activities.

This can be achieved by removing the sql constraint for allocation model to allow negative values.

You can now create allocation with negative balance to match it.

Hope this will be helpful.

Hi, 

By default there is no option for the same. You have to customize the system accordingly, either you can remove the required attribute(make sure that it wont alter any existing functionalities) or you can create a new model for the request and once approved you can create a record in leave model. 

Thanks