Validation logic on Save button click of create invoice page using page composer

Summary:

Is it possible to write validation logic when user clicks on the Save button of the create AP invoice page ?

We have a requirement to populate a Invoice line DFF while creating it and default the Cost center value based on it.

If not, atleast we have to add some validation rule on Save button click of the Create Invoice page to check if the cost center is correctly selected by the user.

Is it possible to do