How much extra money for aides?

As Jeanne says, it can be construed as Medicaid fraud as the employees are getting paid by a federal/state agency & accepting cash from you (I will assume tax free).
The employees should know better.
Yes we know aides are woefully underpaid but nonetheless you shouldn’t do this.
If I were you I would stop this immediately as the aides can lose their jobs & you can get in trouble for not paying income tax on the money you are giving them.

There were strict rules against this in the agency I used.

Bunky, I am moving your post back to the front page. Hopefully caregivers who have given a bonus to the caregivers will be able to give you some suggestions.